Place bread, cut side up, on an ungreased baking sheet. Broil 5 1/2 inches from heat 3 minutes or until lightly toasted. Spread evenly with pesto; set aside.
Heat a large nonstick skillet over medium-high heat until hot. Coat peppers with cooking spray. Cook pepper stir-fry, garlic, salt, and pepper 3 minutes, stirring constantly. Spoon about 1/2 cup pepper mixture over each toasted bread portion; top each with 1/4 cup cheese. Broil 3 additional minutes or until cheese melts.