Crumble beef into a wide frying pan. Add onion and cook over medium heat, stirring often, until meat is browned. Stir in chili powder, black beans and tomatoe sauce. Season to taste with salt and pepper. In a 2 quart round baking dish, alternate layers of buttered tortillas, meat and bean sauce, olives, and cheese. Pour water over top.

Cover and bake in a 400* oven until cheese is melted and tortilla stack is hot in center (about 20 minutes). Makes 4 to 6 servings.