Instructions

In a medium bowl, whisk together the flour, baking powder, and salt. Set it aside.
In a large bowl, add the melted butter, cocoa powder, and espresso powder. Using an electric hand mixer, blend until the mixture is smooth, about 1 to 2 minutes. Add the granulated sugar, brown sugar, and the egg and mix. Add the flour mixture, and mix until everything is well incorporated. Fold in the milk chocolate, white chocolate, and dark chocolate. Allow the dough to chill in the refrigerator for at least 20 minutes.
While the dough is chilling, preheat the oven to 350ºF. Line a baking sheet with parchment paper.
Once the dough is chilled, scoop and shape the dough into balls. Flatten them slightly and arrange them on the prepared baking sheet. Bake the cookies until they begin to firm up around the edges, about 8 minutes. Allow the cookies to cool slightly before enjoying them.
Store in an airtight container for up to 5 days.