Preheat oven to 350ºF. Line a muffin tray with cupcake liners, set aside.

Sift flour, cocoa powder, espresso powder, baking powder, baking soda, and salt in a large bowl and whisk. Set aside.

In a separate medium-sized bowl, whisk together the buttermilk, vegetable oil, eggs, vanilla, granulated sugar, and brown sugar until combined. Pour this mixture into the dry ingredients and whisk until no lumps remain.

Add the hot water to the mixture and whisk, making sure not to overmix. Scoop the cupcake batter into the prepared tins, filling each about 2/3 full. Bake at 350ºF for about 15 minutes, or until a toothpick comes out clean. Allow the muffin pan to cool completely before baking the remaining four cupcakes. Allow the cupcakes to cool completely before frosting.

In a small bowl, add the hot water to the instant coffee to dissolve it, set aside.

In a large bowl, use a handheld electric or stand mixer to beat the butter on medium speed for about 2 minutes, until creamy. Add the powdered sugar, coffee mixture, and heavy cream and beat until combined.

Once the cupcakes are fully cooled, they can be frosted. (We used a piping bag and a Wilton 2D piping tip).