Prepare rigatoni according to package directions and drain. Combine spaghetti sauce, garlic, and fennel. In a greased 12" x 8" (2 quart) baking dish, place 1/2 each of rigatoni, sausage, spaghetti sauce and mozzarella. Repeat layers. Bake 375 F for 25-30 minutes or until hot and lightly brown