Heat oven to 400°F. Lightly spray cookie sheet with cooking spray. In 10-inch skillet, cook sausage over medium-high heat 6 minutes, stirring frequently, until no longer pink. Remove sausage to bowl. In same skillet, heat oil over medium-high heat. Cook bell pepper and mushrooms in oil 5 minutes, stirring frequently, until tender. Add vegetables to sausage. Stir in olives, oregano, basil and red pepper flakes.