Preheat oven to 375. Prepare a 12" pizza pan with cooking spray. Press dough into pan, forming the crust with one inch edges. Prick crust with fork several times. Bake for ten minutes. Sprinkle spinach over crust. In a skillet, cook chicken, onions, bell peppers, and garlic. Cook until chicken is no longer pink. Stir in tomato sauce and oregano. Spoon mixture over spinach in pan. Sprinkle cheeses over top. Bake for 25 minutes, or until crust is lightly brown.