Preheat oven to 350°F (175°C). Line a baking sheet with parchment paper.
Beat butter, brown sugar, and granulated sugar until light and fluffy.
Mix in the egg and vanilla extract.
In another bowl, whisk together flour, cocoa powder, baking soda, and salt.
Gradually add dry ingredients to the wet mixture, stirring until fully combined.
For the filling, melt chocolate chips, then mix in espresso powder and heavy cream.
Scoop cookie dough into small balls, flatten slightly, and add a teaspoon of filling.
Seal the dough around the filling and place cookies 2 inches apart on the baking sheet.
Bake for 10-12 minutes until edges are set.
Let cool slightly before inhaling.