Preheat oven to 425°.
Combine first 4 ingredients; beat with a mixer at medium speed 2 minutes or until well-blended. Stir in spinach, bell peppers, garlic powder, and black pepper.
Unroll pizza crust onto a baking sheet coated with cooking spray; pat into a 14 x 10-inch rectangle. Spread spinach mixture over half of the crust, leaving a 1-inch border. Sprinkle mozzarella and cheddar over spinach mixture. Fold dough over filling; press edges together to seal.
Bake at 425° for 15 minutes or until browned. Cool on a wire rack 5 minutes. Heat pasta sauce in a small saucepan over medium heat. Cut calzone into 6 squares, and top with sauce.