Sugar, for topping Cream butter and sugar. Add eggs, one at a time. Mix until blended. Sift all dry ingredients, add alternately with milk and vanilla. Mash 1/2 cup blueberries; stir into batter. Add remaining whole berries. Grease tins or use liners. Pile batter high. Sprinkle with sugar. Bake at 375F for 30 minutes. Makes 12 muffins.