Spray large skillet with nonstick cooking spray. Heat over medium-high heat until hot. Add onion and bell pepper; cook 3 to 4 minutes or until crisp-tender, stirring frequently. Add meatballs, pasta sauce and 3/4 cup of the cheese. Reduce heat to low; simmer 5 minutes or until thoroughly heated, stirring occasionally. Spoon meatball mixture into crust-lined pan. Sprinkle with remaining 3/4 cup cheese.