Cheesy Squash Casserole

1 pound zucchini
1 pound yellow crookneck or other golden squash
1 1/2 cups chopped onion
2/3 cup chopped red bell pepper
1 cup medium cheddar cheese, shredded (about 3 ounces)
1/4 cup parmesan cheese
1 teaspoon salt
1/2 teaspoon pepper
1/2 cup unseasoned dry bread crumbs
1 egg, beaten slightly

Slice squash and steam in small amount of water until soft. Saute onion and bell pepper in small amount of olive oil. Combine all ingredients, stirring carefully, and place in buttered casserole dish. Bake at 350 degrees until set and top is golden, about 30 minutes. Sprinkle the top with additional cheese or buttered breadcrumbs if desired.