Preheat oven to 375F. Stir together flour, baking powder and salt; set aside. In a large mixer bowl, beat butter and granulated sugar until light and fluffy. Add egg yolks, beat until light.
Gradually stir in lemon juice alternately with dry ingredients (do not overmix). In small mixer bowl, beat egg whites until stiff but not dry; fold 1/3 of egg whites into lemon mixture. Fold remaining egg whites into lemon mixture. Fill paper-lined or greased muffin cups 3/4 full. Combine remaining ingredients sprinkle evenly over top of each muffin. Bake 15 to 20 minutes. Cool 5 minutes; remove from pan. Serve warm. 1 1/2 dozen.