How to Make It
Preheat oven to 400°.
Lightly spoon flour into dry measuring cups; level with a knife. Combine flour and next 5 ingredients (flour through salt) in a medium bowl. Stir in blueberries; make a well in center of mixture. Combine buttermilk, butter, rind, and egg; stir well with a whisk. Add to flour mixture; stir just until moist.
Spoon batter into 12 muffin cups coated with cooking spray; sprinkle evenly with 1 tablespoon sugar. Bake at 400° for 20 minutes or until a wooden pick inserted in center comes out clean. Remove muffins from pans immediately; place on a wire rack.