For the Cupcakes
1. Preheat the oven to 350 degrees F. Line muffin tins with paper liners or spray with nonstick cooking spray.
2. Sift the flour, sugar, cocoa, baking soda, baking powder, and salt into the bowl of an electric mixer fitted with a paddle attachment and mix on low speed until combined.
3. In another bowl, combine the buttermilk, oil, eggs, and vanilla. With the mixer on low speed, slowly add the wet ingredients to the dry. With mixer still on low, add in the coffee and mix until just combined, scraping the bottom of the bowl with a rubber spatula. The batter will be thin.
4. Using a large scoop (about 3 tablespoons), distribute the batter into the prepared muffin tins -filling about 2/3 of the way full.
5. Bake for 18-22 minutes, or until a cake tester comes out clean. Cool in the pans for 15 minutes, then remove them onto a cooling rack and cool completely.
For the Mocha Buttercream
1. In the bowl of a stand mixer fitted with the paddle attachment, beat butter, vanilla, and salt on medium speed until creamy.
2. In a large bowl, sift together the cocoa powder and confectioners’ sugar.
3. Gradually add the dry ingredients to the butter and mix at low speed until fully incorporated. Scrape down the sides of the bowl as needed.
4. Once all of the dry ingredients have been incorporated, add in 3 tablespoons of cold coffee. Turn the mixer up to medium speed and beat the buttercream for about 5 minutes, scraping down the sides of the bowl as needed. If you want your frosting a little thinner, gradually add in more coffee, 1 teaspoon at a time until you reach the desired consistency.
5. Frost your cooled cupcakes and garnish with toasted shaved coconut.