Seashell-Provolone Casserole - cooking recipe

Ingredients

3 medium onions, firmly chopped
1/4 c. margarine, melted
1 1/2 to 2 lb. ground beef
1 (15 1/2 oz.) jar plain spaghetti sauce
1 (16 oz.) can stewed tomatoes
1 (4 oz.) can mushroom stems and pieces, drained
1 tsp. garlic salt
1 (8 oz.) pkg. seashell macaroni
1 (8 oz.) pkg. Provolone cheese, sliced
3 c. commercial sour cream
1 c. (4 oz.) Mozzarella cheese, shredded

Preparation

Saute onion in butter in a large skillet just until tender. Add ground beef, cook until browned, stirring to crumble meat. Add spaghetti sauce, tomatoes, mushrooms and garlic salt to meat mixture.
Stir well and simmer 20 minutes.
Cook macaroni according to package directions except reduce salt to 1 1/2 teaspoons, drain.