Place mushrooms, stem side down, on a greased baking sheet; drizzle with oil. Bake at 350° for 20-25 minutes or until tender, turning once., Meanwhile, cook sausage over medium heat until no longer pink; drain. Stir in the pizza sauce, pepper, onion, mushrooms, Parmesan cheese and garlic. Divide among mushrooms; sprinkle with mozzarella cheese. Broil 2-3 in. from the heat for 1-2 minutes or until cheese is melted. Sprinkle with basil if desired.