Preheat oven to 425°.
Lightly spoon flour into a dry measuring cup; level with a knife. Combine flour, oats, and next 4 ingredients in a bowl; stir well.
Combine egg and next 5 ingredients; stir well with a whisk. Add to flour mixture, stirring just until moist.
Spoon batter into 12 muffin cups coated with cooking spray. Sprinkle batter evenly with cinnamon-sugar.
Bake at 425° for 18 minutes or until muffins spring back when touched lightly in center.
Remove muffins from pan immediately; place on a wire rack.