Sautee onion, celery and bell pepper in butter and olive oil.
Cook until onions are soft and translucent. Add tomatoes, both sugars and both basils. Mix cornstarch in vinegar and add to tomato mixture.
Bring to a boil. Add salt and pepper and pour into a greased casserole. Mix together breadcrumbs and butter.
Top tomatoes with breadcrumbs and bake at 350-degrees for 30-45 minutes or until filling is bubbly and breadcrumbs are lightly browned.