Brown beef with onions and garlic; srain off fata. Stir in spaghetti sauce, stewed tomatoes and mushrooms. Simmer about a half hour. Layer as follows in a Dutch oven or casserole: half shells, half sauce, half sour cream, provolone cheese. Repeat, ending with mozzarella. Bake a half hour or so at 180ºC . until heated through and bubbly. Taste of Home Ground Beef Collection 1996 Edition