This soup is an excellent way to get your kids to eat more vegetables! It is also a perfect soup for Spring!
Line cookie sheet with foil; brush foil with olive oil. Spread tomatoes over pan & brush with oil; sprinkle with salt & pepper. Roast tomatoes at 400 degrees for 30 minutes; set aside.
Melt 4 tablespoons butter in large stock pot over medium-high heat. Saute onions & leeks until tender, about 5 minutes. Add remaining vegetables; sauté additional 10 minutes over medium heat. Add more butter or olive oil if necessary.
Add broth to vegetables; stir in roasted tomatoes and white beans. Bring to boil; reduce heat and simmer 30 minutes.
Melt remaining 3 tablespoons butter in medium saucepan over medium heat. Whisk in flour to create roux; add milk & whisk continuously until milk begins to bubble and thicken. Reduce heat to low; stir in dill. Remove from heat. Add milk mixture to soup; bring just to boiling then reduce heat and simmer 15 minutes.