Preheat oven to 400°.
Lightly spoon flour into dry measuring cups; level with a knife. Combine flour and next 5 ingredients (flour through chocolate) in a medium bowl; stir well with a whisk. Make a well in center of mixture. Combine milk, butter, and egg; stir well with a whisk. Add to flour mixture, stirring just until moist.
Spoon about 1 tablespoon batter into each of 12 muffin cups coated with cooking spray. Spoon 2 teaspoons preserves into center of each muffin cup (do not spread over batter); top with remaining batter. Sprinkle evenly with 1 tablespoon sugar.
Bake at 400° for 22 minutes or until muffins spring back when touched lightly in center. Remove from pan. Cool completely on wire rack.