Cupcakes decked in feathery coconut add flair to an all-white dessert table.
Preheat oven to 325 degrees. Line 2 standard 12-cup muffin tins with paper liners. Into a medium bowl, sift flour, baking powder, salt, and baking soda.
In the bowl of mixer fitted with the paddle, mix butter and sugar on medium until pale and fluffy, 3 to 5 minutes. With mixer running, add eggs and vanilla; mix until combined.
With mixer on low, add 1 cup flour mixture; mix until combined. Add 1/2 cup buttermilk; mix until combined. Add remaining flour mixture and buttermilk in 3 alternating batches, ending with the flour.
Divide batter among muffin cups. Bake, rotating tins about halfway through, until light golden brown and a cake tester inserted into centers comes out clean, 25 to 30 minutes. Transfer tins to a wire rack; let cool.
Put coconut in a shallow bowl. Frost each cupcake with about 3 tablespoons buttercream, and press frosted tops into coconut to coat.