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How to Make a Sandcastle Cake

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How to Make a Sandcastle Cake | Sandcastle Cake | Easy Sandcastle Cake Recipe | Sandcastle Cake Toppers | Creative Cakes | Beach Themed Cakes

Oh, the cake!

I knew as soon as we decided on a mermaid theme for Trouble’s 4th birthday that a sand castle cake would be perfect. I had seen a few really photos on Pinterest, I just couldn’t find any detailed instructions. Since paying hundreds of dollars for a professionally decorated cake was out of the question, I decided to go with plan B: wing it!

I kinda prefer plan B anyways. 😉

Let me just start by saying that I am not a professional baker, or even anything close to it, but what I lack in technical skill I make up for with sheer determination. I’m not going to lie, this cake took forever and a day to make. It was truly a labor of love. But, when all is said and done I was so happy I put in the time because it truly was the focal point of the entire party. Luckily I already had most of the cake ingredients already on hand in my stockpile.

Now, a word about cakes. I am not a professional baker, but I do love to bake. After trying lots of from-scratch cake recipes, I decided that boxed cake mixes are much easier, the texture is often better, and they taste just as good. However, the frosting makes HUGE difference! I almost always make this homemade cream cheese buttercream frosting for my cakes. It is super easy and SO much better than the store-bought stuff!

To make a sandcastle cake, assemble the ingredients: cake mix, eggs, butter, cream cheese, confectioners sugar, oil and graham crackers. Here is what you need:

4 boxes of cake mix
vegetable oil
graham crackers
white or brown sugar
4 sugar cones
5 coconut marshmallows (optional)
1 large batch cream cheese buttercream frosting
candy melts
seashell candy mold & starfish candy mold
9″ square cake pan
2-8″ round cake pans
1-6″ round cake pan
metal cocktail shaker
paper flags
wooden skewers

Pipe melted white chocolate into seashell molds to decorate your sand castle cake.

Step 1: Make the white chocolate seashells & starfish. This is a very easy process! Simply melt the candy melts in the microwave per the bag instructions, then place melted chocolate into a decorating bag, cut off a small hole at the tip, and pipe into the molds. Place in refrigerator to harden for 15-20 minutes, then pop out of the mold. I found that one bag of melts was enough to exactly fill my starfish mold and seashell mold 1 time each.

Toast the coconut for the sand mixture that will cover the outside of your cake.

Step 2: Toast coconut for the sand mixture. Preheat oven to 350 degrees, then lay out several cups of coconut on a baking sheet. Toast in oven for 10-12 minutes until coconut is completely golden brown, stirring several times throughout the process to ensure it is toasted evenly.

Pulse graham crackers and toasted coconut in the food processor to make the sand for your cake.

Step 3:  Make “sand” mixture. Place 2-3 packages graham crackers, toasted coconut, and several cups of white or brown sugar (I used white to get a lighter sand) into a 12 cup food processor and process until mixture resembles a fine sand.

The pulsed graham crackers and coconut should be the consistency of sand when you finish.

Step 4:  Begin making cakes according to the box directions. This process will take a while since you will have to re-use the same pans multiple times. Be sure to grease and flour your pans VERY well each time, especially the cocktail shaker.

You will need an assortment of pans for this cake, including a metal cocktail shaker.

Here is the breakdown of how I baked them:
Box 1 (strawberry): square pan, 6″ round pan, cocktail shaker; reserved small amount in bowl. (See photo below)
Box 2 (strawberry): same as Box 1
Box 3 (coconut): 2 8″ round pans, cocktail shaker filled with excess strawberry from boxes 1 & 2
Box 4 (coconut): square pan, 6″ round pan, cocktail shaker 
Pour the cake batter into each of the pans, including the cocktail shaker. Be sure to tap out any air bubbles before baking.

Tip: Before baking, tap each cake pan firmly on counter several times to release any air bubbles. This will improve your cake’s texture and help it to bake flatter!

When the layers are finished baking allow them to cool on a rack before you build your sandcastle cake.

Step 5: Let all your cake layers cool completely; refrigerate if desired to make them firmer and easier to work with.

Use cones covered in frosting to make the turrets for your castle. Roll them in the toasted coconut and graham cracker crumbs.

Step 6: Make your “turrets” and “battlements” out of sugar cones and marshmallows. First, cut the tip of the cone with a sharp knife enough so that the flags will fit in the hole. Next, smooth frosting over the cone and roll in “sand” mixture until it is completely covered. Repeat process with marshmallows. Set aside or refrigerate until needed.

Insert flags in each cone to go on top of your sandcastle cake.

Step 7:  It is almost time to start assembling your cake, but first you need a base! Cut out a piece of cardboard in a rounded wavy rectangle as shown.

Cut a large cardboard base for your sandcastle cake.

Step 8: Make your “towers.” Cut the bottom of your cooled and chilled cocktail shaker cakes so that the stand up straight. Roll in sand mixture, much like you did with the sugar cones and marshmallows. I found this was easiest to do by sticking a few skewers through the tower so I had something to hold on to. Be sure to get the top as well!

Make your towers by rolling them in the coconut and graham cracker mixture.

Step 9:  It is finally assembly time! If all went according to plan, you should have 3 square layers for your base. Level the layers with a cake leveler if necessary, then place the first layer on your cardboard base, add a thick layer of frosting, the add the second layer, followed by more frosting and the third layer. Frost most of the top and the sides, then carefully add “sand” so that it sticks to the frosting. The goal is to get the whole cake covered with sand.

Layer your sandcastle base and cover the sides with the graham cracker crumbs.

Step 10:  Level the two 8″ round cakes if necessary. Lay the first cake flat side down on top of square cakes. Spread a thick layer of frosting, then add the second 8″ cake flat side up. Spread sides and top edges with frosting, then once again cover the frosting with sand mixture.

Layer the round cakes and cover them with the frosting and graham cracker sand.

Step 11: Repeat this process with the three 6″ round layers. For that section, I found it easiest to assemble the three layers on the counter, then frost and roll the sides in sand like with the tower pieces. Once the top 6″ round layer is in place, push some skewers through the top of cake through all layers to add extra stability, then frost and sand the top of the cake.

Layer the three 6 inch cakes, frost and cover with graham cracker sand.

Step 12:  Once the entire cake has been frosted and sanded it is time to add the towers to the four corners. Use the cocktail shaker to cut out each cake corner, then spread frosting over exposed cake pieces and press tower into place. Add a dollop of frosting to the top of the tower to secure turret in place, and push straw flag through the cone into cake so it stays in place. Cover any cracks or exposed frosting with sand.

Add the cake towers to your sandcastle cake.

Step 13:  Add the battlements to the top of the cake by placing a toothpick in each one and pressing into place.

Insert a toothpick into the battlements and add them to the top of the sandcastle cake.

Step 14:  Add the finishing touches to your cake! Use the seashells and starfish to embellish the top and sides, then, when the cake is in place on the table, use remaining sand to cover the cardboard and make the cake look like it is sitting in a patch of sand. Your guests–and your guest of honor–will be blown away!

Cover the cake and base with the remaining graham cracker sand.

Add white chocolate shells around the sandcastle cake to decorate this beachy treat!

This sandcastle cake was the perfect centerpiece for my daughter's beach-themed mermaid party!

*   *   *

Do you bake your own birthday cakes? What’s the most creative cake you’ve made (or ordered)?


  1. June 12 at 09:31AM

    Wow. I love your sandcastle cake! The sand mixture is such a great idea. My daughter had a Hawaiian themed party and I used brown sugar to give the appearance of sand on part of her cake but you certainly couldn’t cover a cake in it. I almost always make my kid’s cakes. I’ve made Hobbit holes and turtle cakes. I think the most creative and my favorite was the pirate ship cake I make for my youngest son. You can see it here:

    • Ruth Soukup
      June 17 at 01:57PM

      So cute! Thanks for sharing Charlotte!

  2. Nicole
    June 12 at 12:20PM

    What would you suggest in place of coconut. Coconut won’t work for our family 🙁

    • Sandra
      June 14 at 01:37AM

      Just use vanilla sandwich cookies and try to crush so fine that you can’t see the white filling anymore. 🙂

    • Ruth Soukup
      June 14 at 09:11AM

      I would just blend the graham crackers and white or brown sugar in the food processor and skip the coconut completely. It just won’t be quite as “speckled” looking but it will still look just like sand! 🙂

    • Anonymous
      October 12 at 10:39AM

      Use vanilla Oreos, that’s all you need!

  3. Lovely structure and after it was finished didn’t you want it to be a real cake. Would have tempted though

  4. June 13 at 07:52AM

    What a fun idea! It would be a pleasure to have you join my weekly link party and share this.

  5. June 13 at 10:00AM

    Such a cute cake!! Fun idea! I love your tablescape too! I’m sure she had a blast!

    • Ruth Soukup
      June 14 at 09:12AM

      Thanks Kathryn! It was definitely a very fun party! 🙂

  6. June 13 at 02:35PM

    Wow! This is adorable! Such a cute idea and it turned out to look so professionally done!

    • Ruth Soukup
      June 17 at 01:54PM

      Thank you Lisa!

  7. Wow, impressive! Your cake is beautiful and looks quite realistic. And I agree with making your own icing. I like to bake too but sometimes I use box mix… but NEVER store bought icing again!

    • Ruth Soukup
      June 14 at 09:12AM

      Yes, the icing is KEY! 🙂

  8. bri
    June 16 at 01:13PM

    is there another option besides coconut? I am allergic but love this idea…..

    • Ruth Soukup
      June 17 at 01:55PM

      I would just omit the coconut and make the sand mixture using sugar and graham crackers. It will look almost the same, it just won’t have the darker flecks. You can use any flavor of cake mix!

  9. June 19 at 01:28PM

    I can not believe how much that looks like an actual sand castle!! Although my hubby may shake his head at me adding another dish to our 4th of July party – I am thinking this one needs to be included!! 🙂 Pinning right now. Can’t wait to try it – it sounds just as good as it looks. It would be great if you could link this recipe up at Tasty Tuesdays this week. 🙂

  10. Vicki
    July 14 at 07:40AM

    This is one of the best beach themed cakes I’ve ever seen! Amazing!

  11. July 16 at 04:59PM

    So cute! I love this for a beach, luau, or mermaid party! I am adding it to a round up of beach themed crafts and ideas on my site next week. It also made it into my Looksi Curated Collection for Looksi on Friday, July 19th.

  12. Sharon
    July 28 at 09:32PM

    I took classes in cake decorating, this is a great looking cake. One thing they taught us is never use oil on your pans, use Crisco, the will come loose better and you can buy if you want insulators to go around the pans so the cake rises more even. This is a great cake for a beach themed party, get out the little umbrellas and enjoy 🙂

  13. July 31 at 12:14PM

    I’m the Editorial Assistant for Fun Family Crafts and I wanted to let you know that we have featured your awesome cake! You can see it here:

    If you would like to display a featured button on your site, you can grab one from the right side bar of your post above. Thanks for a wonderful project idea!

  14. August 1 at 03:15AM

    This is so pretty! All hard work and the long process will be paid off after seeing this beautiful cake. I haven’t seen any kind of cake near to this idea, thanks for sharing this with us! And kudos for this brilliant cake.

  15. Sarah
    August 16 at 08:28AM

    Thank you for your awesome mermaid party ideas! My six year old picked your cake as her favorite one on Pinterest, and we set out to recreate it! What a huge hit! We also used your free printable invitation. Thanks for helping us out with your terrific ideas.

    • Ruth Soukup
      August 17 at 06:35AM

      I’d love to see pictures Sarah! You’re very welcome! 🙂

  16. Sue Johnson
    February 9 at 04:21PM

    Hi Ruth, I love this cake but need to make on for 40-50 people any recommendations on pan sizes to do this and how many cake mixes? You are brilliant!

    • Anonymous
      February 12 at 10:10AM

      Hi Sue
      You should be able to follow the recipe as is for your for your large party. We had a party of 50 guests and had left-overs.
      I hope your guests enjoy!

      • Jennifer
        February 17 at 06:11PM

        I would like to do a version of your cake, but much smaller. Do you have any tips on downsizing the recipe? I only need to feed 20 guests. Its the perfect cake for my soon to be 2 year old’s Underwater Party. Thanks!

        • July 13 at 08:57PM

          I would love to hear suggestions for a smaller cake too! Also, is the cocktail shaker necessary? Could I use something else to bake the towers in? Thank you!!

          • Ruth Soukup
            July 14 at 08:18AM

            Amazon has a super cute castle cake mold: If you don’t have all the different pan sizes I listed. 🙂

          • Jennifer
            July 14 at 10:42AM

            Ann- I winged it. I made enough batter (from scratch) for 2 cakes and then I used a 10×10 pan, a 8″ round cake pan, and 4 ice cream cones to make my castle. I didn’t use a cocktail shaker.
            Best of luck to you!

  17. April 24 at 10:35AM

    How cleaver! I’d love to see the decorations that went along with the cake. Thanks for sharing!

  18. July 3 at 06:26PM

    I love it, I will actually use your tips to make the Dune cake for this weekend friends party..

  19. Samantha
    August 18 at 04:14PM

    I want to attempt this for my daughter’s 1st birthday but I’m terrified. How long did you bake the various sized pans? Each would be different times, no? I suppose I’m asking mostly for the shaker and 6″. Also, how many packages of coconut vs. how many cups of sugar for 2-3 packages of grahams? I can imagine running out of “sand” and by then being totally DONE. Any specifics would be SO helpful!

  20. Carrie S
    April 27 at 11:13AM

    This great! Thank you so much! My husband and our daughter share a birthday so I always try to make a party that works for both of them…this year will be The Little Mermaid, her cake will have scales and a mermaid and his will be a sandcastle – I am so glad I found your tutorial!! I want to make this the day before, should I store overnight in the fridge? I’m worried about the coconut mixture getting soggy

  21. Lisa
    May 8 at 11:13AM

    Could you make the “sand” without coconut? My daughter is does not like coconut.
    Also, Do you add anything to the cake mixes to make them more firm? I notice that my cake mixes turn out quite “airy”.
    Thanks! It looks amazing! This is project for the weekend.

  22. Amy
    February 20 at 07:59PM

    How far in advance would you recommend making the cake?

  23. Natalie
    June 8 at 07:54PM

    Hi, this cake looks amazing and I am going to use it as inspiration for a cake for my daughter’s birthday. May I just ask what sort of coconut you used? Was it dessicated coconut from a packet or did you crack up fresh coconuts and toast them yourself? I am not sure I can be bothered with all that hassle! Thanks

    • Ruth Soukup
      June 8 at 09:50PM

      It was bagged coconut that I toasted. 🙂

  24. T Courtney
    August 18 at 06:55PM

    Just made this cake…. so awesome. Came out better than I expected. Thanks for such awesome step by steps!!!

  25. Amy
    October 28 at 01:31AM
  26. Tara
    April 8 at 11:00AM

    I’m having a hard time finding the paper flags. Do you remember where you got them?

    • Ruth Soukup
      April 9 at 12:00PM

      I made the paper flags out of scrapbook paper and paper straws. 🙂

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