Preheat oven to 350ºF. Line a muffin pan with cupcake liners. Set aside.

Sift the flour, cocoa powder, baking soda, baking powder, espresso powder, and salt into a large bowl and whisk until combined. Set aside.

In a large glass measuring cup, whisk together the buttermilk, vegetable oil, eggs, egg yolk, vanilla, granulated sugar, and brown sugar until combined. Pour the wet ingredients into the dry ingredients and use an electric handheld or stand mixer on low speed to mix until mostly combined. Add the hot water and mix on low speed until fully incorporated. *Be sure not to overmix!

Scoop the cupcake batter into the prepared tins, filling each about 2/3 full. Bake at 350ºF for 13-15 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 large bowl, use an electric handheld or stand mixer to beat the butter and cream cheese on medium speed for 2 minutes, until creamy. Add the powdered sugar, heavy cream, vanilla extract, and mix on low speed until combined. Then fold in the cookie crumbs using a spatula.

Once the cupcakes are fully cooled, they can be frosted. (We used a piping bag and a Wilton 8B tip to frost our cupcakes!)