Heat oven to 425. Spray a lg pizza pan w/ cooking spray. Place 1 pie shell flat on pizza pan. In lg skillet, heat oil over medium heat. Add onion and bell peppers. Cook until tender, stirring occasionally. Stir in chicken, corn and fajita seasoning. Remove from heat. Spoon mix onto pie shell, leaving a 1" border. Sprinkle evenly w/ cheese. Brush w/ beaten egg. Place 2nd pie shell over filling. Press edges together w/ fork to seal. Bake about 25 min, or until golden brown. Cut into wedges and serve w/ sour cream and salsa.