1/2 pound ground pork sausage
2 cups Bisquick baking mix
1/2 cup chopped onion
1/2 cup very hot water
3/4 cup milk
1 tablespoon butter
1 tablespoon flour
1 1/2 cups shredded cheese of choice (e.g., mozzarella, cheddar, or a blend)
Salt and pepper to taste
4 eggs (optional)