Cook pasta according to package directions. Meanwhile, in a large saucepan, cook the sausage, mushrooms, red pepper and garlic over medium heat until meat is no longer pink; drain. Stir in 1 cup spaghetti sauce. Remove from the heat and set aside.
Drain pasta and rinse in cold water. Spread remaining spaghetti sauce into a greased 13-in. x 9-in. baking dish. In a small bowl, combine the cheeses, egg, basil and garlic powder. Spoon heaping tablespoonfuls into shells. Arrange shells in dish. Spoon sausage mixture into shells.
Cover and bake at 350° for 40-45 minutes or until bubbly. Cut roasted peppers to resemble tongues. Add a tongue to each shell and olives for eyes.