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

In a medium bowl, whisk together flour, cocoa powder, baking powder, baking soda, and salt. Set aside.

In a larger mixing bowl, use an electric mixer to cream together the softened butter and granulated sugar until light and fluffy (about 2-3 minutes).

Beat in the egg, vanilla extract, and cooled brewed coffee until well combined.

Gradually add the dry ingredient mixture into the wet ingredients, mixing until just combined.

Drop rounded tablespoons of dough onto the prepared baking sheets, leaving space between each scoop.

Bake for 10-12 minutes, or until puffed and set. Let cool on baking sheets for 5 minutes before transferring to wire racks.

For the filling, cream together powdered sugar, softened butter, milk, and vanilla extract until smooth and fluffy.

Spread a generous amount of filling on the flat side of one cookie and top it with another cookie.

Repeat with remaining cookies and serve.