Preheat your oven to 350 degrees F. Line a cupcake tin with cupcake liners.

Add the cocoa powder to a medium-sized bowl. Whisk in the boiling water (it will be pretty thick). Set aside.

Add the butter to a large bowl. Cream the butter using an electric mixer on low until light and fluffy.

Gradually add in the sugar, mixing until light and fluffy, scraping down the sides to ensure it’s fully combined.

Add the coffee extract. Add the beaten eggs a little at a time, mixing in between each addition until fully incorporated. Scrape down the sides to make sure it is fully combined.

In a separate large bowl, combine the flour, cornstarch, baking soda, and salt.

Add the milk to the bowl of the cocoa mixture and whisk to combine.

Add the flour and cocoa mixtures to the butter mixture a little at a time, alternating between the two, and mixing to combine before adding in the next amount. Start and end with the flour mixture, mixing until fully combined.

Fill each cupcake tin about 2/3 of the way full.

Bake at 350 degrees F for 20 minutes or until a toothpick inserted into one of the center cupcakes comes out clean.

Let cool for 10 minutes in the cupcake tins, then remove to a wire rack to cool completely. Repeat with the remaining batter.

While the cupcakes cool, prepare your frosting. Add to a piping bag (or ziptop bag with a bottom corner cut off, and pipe on to each fully cooled cupcake.