Gather all your ingredients, ensuring the unsalted butter and the egg are at room temperature.

In a medium bowl, whisk together the flour, cocoa powder, espresso powder, baking soda, and kosher salt.

In a large bowl, beat the room temperature butter, granulated sugar, and light brown sugar together on medium-high speed for 2-3 minutes until light and fluffy.

Add in the egg, vanilla extract, rum extract, and milk, and beat until smooth.

Slowly add the dry ingredients to the wet mixture, mixing until just combined.

Cover the dough with plastic wrap and refrigerate for at least 2 hours, preferably overnight.

Preheat your oven to 350°F (175°C) and line baking sheets with parchment paper.

Scoop dough onto prepared baking sheets, placing them about 2-3 inches apart.

Bake for 10-12 minutes until edges are set and tops are slightly soft.

Cool cookies on the baking sheet for about 5 minutes before transferring them to a cooling rack.

Melt the white chocolate in a microwave-safe bowl in 30-second increments, stirring until smooth.

Dip half of each cookie in the melted white chocolate and place on parchment paper, adding 1-3 coffee beans on top.

Allow the cookies to set at room temperature or speed up the process in the freezer.