Preheat oven to 425°.
Lightly spoon flour into a dry measuring cup; level with a knife. Combine flour and next 5 ingredients in a bowl.
Combine buttermilk, corn, peppers, and egg. Add buttermilk mixture to flour mixture; stir just until moist.
Spoon batter into 12 muffin cups coated with cooking spray, filling three-fourths full. Bake at 425° for 15 to 17 minutes or until lightly browned. Remove from pans immediately; place on a wire rack. Serve warm with spread.