1 (10.75 ounce) can condensed cream of mushroom soup
1/2 cup sour cream
3 medium carrots, grated
1 (5.5 ounce) package croutons
1/2 cup butter
8 ounces shredded mozzarella cheese
Preheat oven to 350 degrees F (175 degrees C).
Boil squash and onion in a small amount of water for 5 minutes. Place boiled squash and onions in a 9x13 inch baking dish. Mix in soup, sour cream, carrots, croutons, and butter. Top with Mozzarella cheese.
Cover dish and bake in preheated oven for one hour.