Meanwhile, heat barbecue sauce and garlic in medium skillet over medium heat. Add peppers and onion; cook, stirring occasionally until peppers are crisp-tender and sauce has thickened slightly. Top prebaked crust with 1 cup of the cheese and chicken. Top with vegetable mixture and sprinkle with remaining cheese. Bake an additional 10-15 minutes or until cheese is melted and bottom of crust is golden brown.