Cook spinach according to package directions; drain well. Place spinach in a large bowl.
Heat a large nonstick skillet over medium-high heat. Coat pan with cooking spray. Add chopped onion and bell pepper; sauté 2 minutes or until tender.
Add onion mixture, eggs, and egg whites to spinach. Add flour and next 5 ingredients (through sour cream); stir to combine. Spoon mixture into a 9-inch pie plate coated with cooking spray. Sprinkle evenly with paprika. Bake at 350° for 30 minutes or until set. Let stand 5 minutes before serving.