1-First Step: Prep your pan and oven Start by preheating your oven to 300°F (148°C). Line a standard cupcake pan with paper liners so the cupcakes release easily after baking. This small step saves time later and helps the cupcakes bake evenly. Set the pan aside while you mix the batter.

2-Second Step: Mix the dry ingredients In a medium bowl, combine the flour, sugar, cocoa powder, baking soda, and salt. Whisk them together until the mixture looks evenly mixed and there are no clumps of cocoa. This helps the chocolate flavor spread evenly through every cupcake.

3-Third Step: Stir together the wet ingredients In a second bowl, whisk the egg, milk, vegetable oil, and vanilla extract until smooth. The oil is important here because it helps the cupcakes stay soft even after a day or two. If you are baking ahead for an event, this is one of the reasons the recipe works so well.

4-Fourth Step: Bring the batter together Pour the wet mixture into the dry ingredients and stir just until combined. You do not want to overmix, since that can make the cupcakes dense. Once the batter looks blended, add the hot water and mix again. The batter will be thin, and that is exactly what you want.

5-Fifth Step: Fill the cupcake liners Spoon the batter into the liners, filling each one about halfway. This is an important step because the batter rises as it bakes. If you fill the liners too much, the cupcakes can overflow or sink in the center. For even portions, use a scoop or measure by eye as carefully as possible.

6-Sixth Step: Bake until set Bake the cupcakes for 18 to 23 minutes, or until a toothpick inserted in the center comes out with moist crumbs. Since ovens can run hot or cool, start checking near the 18-minute mark. You want the cupcakes baked through, but still soft and tender.

7-Seventh Step: Cool the cupcakes properly Let the cupcakes cool in the pan for 2 minutes, then move them to a wire rack. This short rest helps them firm up without getting stuck in the liners. After that, let them cool completely before adding frosting. If you frost them too soon, the buttercream can slide right off.

8-Eighth Step: Make the cookie buttercream Beat the unsalted butter until smooth and creamy. Add half of the powdered sugar and beat again until the mixture looks fluffy. Next, mix in the vanilla extract and 2 tablespoons of heavy cream. Once that is blended, add the cookie crumbs and then the remaining powdered sugar. Beat until smooth. If the frosting feels too thick for piping, add 2 to 3 more tablespoons of heavy cream a little at a time.

9-Ninth Step: Decorate and serve Pipe the frosting onto the cooled cupcakes and top each one with a whole cookie. If you want a bakery-style look, use a large star tip and swirl the frosting high. These cupcakes are ready to serve right away, but they also hold up well for gatherings later in the day.