Makes 14 cupcakes

Position a rack in the middle of an oven and preheat to 350°. Line fourteen 1/2-cup muffin-pan cup with paper liners.

In a medium bowl, sift together the flour, sugar, baking soda and salt. In a large bowl, whisk together the mashed banana, melted butter, egg and buttermilk until well blended. Add the flour mixture and whisk just until combined. Stir in the chocolate chips. Spoon an equal amount of the batter into each prepared muffin cup.

Bake until a toothpick inserted into the center of a cupcake comes out clean, about 25 minutes. Remove from the oven and immediately invert onto a rack. Turn the cupcakes right-side up. Let cool completely.

To serve, spread about 1 tablespoon buttercream over each cupcake. To store, pack in a single layer in an airtight container and refrigerate for up to 2 days. Bring to room temperature before serving.