Macaroni Cheese and Hamburger Casserole

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(My mom created this recipe--it has to be our family's all-time favorite dinner.)

1 lb. ground beef
½ onion, chopped
1 teaspoon parsley
½ teaspoon salt
¼ teaspoon pepper
1 15-oz. can tomato sauce
1 lb. elbow macaroni, cooked and drained
2 cups shredded cheddar cheese, divided

Brown ground beef and onion; add spices as meat is browning. Add tomato sauce and heat through. Combined cooked macaroni, meat sauce and 1½ cups of the cheese and mix well. Sprinkle remaining cheese on top and allow to melt.