Heat oven to 325°. Place paper liners in cups of mini muffin pans (36 total).
In a small bowl, whisk together flour, baking powder and salt. In a
large bowl, beat butter until smooth. Add sugar and beat until fluffy,
about 2 minutes. Add egg whites, one at a time, beating well after each.
Beat in vanilla. On low, beat in half the flour mixture, then 3/4 cup
water. Beat in remaining flour mixture.
Divide batter evenly among prepared cups. Bake at 325° for 18 minutes.
Frost and decorate as desired.