3 med. onions, chopped
1/4 c. butter
2 lbs. ground beef
1 (32 oz.) jar plain spaghetti sauce
1 (16 oz.) can stewed tomatoes
1 tsp. garlic salt
1 (8 oz.) pkg. sliced provolone cheese
3 c. sour cream
1 c. Mozzarella cheese
16 oz. pkg. large shells (3/4 pkg.)

Saute onion with butter. Add beef and cook. Add sauce and tomatoes and garlic salt. Simmer 20 minutes. Cook shells. Layer 1/2 shells, 1/2 sauce, 1/2 provolone cheese, 1/2 sour cream, 1/2 Mozzarella cheese. Repeat. Bake at 350 degrees for 30 minutes covered. Uncover and bake 15 additional minutes.