Sandwich Filling

½ pound lean ground beef

8 ounces tomato sauce

½ cup finely chopped onion

½ cup chopped black olives

¼ cup chopped pimento peppers

1 (8 ounce) can mushrooms, drained and chopped

8 ounces extra-sharp Cheddar cheese, shredded

1 ½ teaspoons chili powder

salt and ground black pepper to taste

4 hamburger buns, split

Preheat oven to 400 degrees F (200 degrees C).

Cook and stir ground beef in a large skillet until well browned, about 10 minutes; drain fat. Place cooked beef in a large bowl. Stir in tomato sauce, onion, black olives, pimentos, mushrooms, Cheddar cheese, chili powder, salt, and black pepper.

Spoon sandwich filling on hamburger bun bottoms, spreading to the edges. Filling should be approximately 1/2 thick in the center of the sandwich.

Bake in the preheated oven until the edges start to bubble, 5-10 minutes. Turn oven to Broil and continue to cook until heated through, about 3 minutes.