Heat oven to 425. Spray rectangular pan, 13x9x2 inches, with cooking spray. Place melted butter in large shallow bowl.
Make 2-inch horizontal slit in each chicken breast. Stuff 1 tablespoons cheese in each pocket. Dip each chicken breast into butter; sprinkle with sesame seed.
Heat oil in 12-inch nonstick skillet over medium heat. Cook chicken in oil until brown on both sides. Place chicken in pan. Drizzle with any remaining butter.
Bake uncovered 15 to 20 minutes or until chicken is no longer pink in center. Meanwhile, prepare Roasted Red Pepper Sauce; keep warm. Serve chicken in pool of sauce, or drizzle sauce over chicken.
To prepare sauce: Place all ingredients except sour cream in mini food processor or blender. Cover and process until smooth. Heat mixture in 1-quart saucepan over medium heat, stirring occasionally, until hot; remove from heat. Strain if desired; stir in sour cream.