Preheat oven to 400F. Spray a 1-quart baking dish with oil. Set aside.
Cook bacon in a skillet over medium heat until crisp; remove with a slotted spoon drain on paper towels. Remove all but about 1 tablespoon of the bacon fat from the pan.
Saute diced onion in bacon fat until softened, about 5 minutes.
Stir together all ingredients until well combined. Pour into prepared pan.
Bake, uncovered, for 45 minutes or until sauce has thickened.