1. Preheat oven to 375°. Split pitas in half horizontally to make 4 rounds. Arrange pitas on a baking sheet, cut side up. Bake 6 minutes or until lightly toasted. Remove from oven. Increase oven temperature to broil.
2. Meanwhile, melt buttery spread in a 10-inch nonstick skillet over medium-high heat; add onion, and cook, stirring occasionally, 5 minutes or until onions begin to brown. Add roasted peppers and chicken, and cook, stirring constantly, 2 minutes or until thoroughly heated. Stir in Parmesan cheese, salt, and, if desired, basil.
3. Top pitas with chicken mixture; sprinkle with mozzarella cheese.
4. Broil 5 inches from heat 2 to 3 minutes or just until cheese is melted. Cut into quarters. Garnish, if desired.