1. Heat oven to 350 degrees . Line a 12-cupcake baking pan with cupcake liners. Blend boiling water and cocoa in a small bowl; cool for 5 minutes. In a medium bowl, combine flour, baking soda, baking powder and salt.
2. In a large bowl, on high speed, beat butter and sugar until light and fluffy. Add eggs and vanilla and beat well. Reduce speed to low and alternately beat in flour mixture and buttermilk until just blended. Add cocoa mixture and mix well. Divide batter among prepared cupcake liners.
3. Bake at 350 degrees for 22 to 24 minutes, until a toothpick inserted in center comes out clean. Cool completely in pan on a wire rack. Pipe Fluffy Frosting and top with sprinkles, if desired.