Beat together the butter and sugar in a large bowl with a hand held mixer or stand up mixer until creamy.  Then add in the egg and vanilla extract until combined.

In a separate bowl, whisk together the flour, cocoa powder, baking powder and salt.

Slowly add the flour mixture to the butter mixture and mix on low speed until just combined.  Be careful not to over mix.

Then add in the milk and stir until combined.

From the cookie dough into 2 logs that are approximately 1 1/2 inches in diameter. Wrap each log in plastic wrap and refrigerate for at least 2 hours.

Preheat the oven to 350 degrees Fahrenheit and line baking sheets with parchment paper.

Remove the logs from the refrigerator and slice into 1/8 inch thick slices to form them into cookies. Place them on the prepared baking sheets.

Bake for 10-12 minutes, rotating the pans halfway through the baking time. Bake until the cookies are just set (look firm). These cookies are dark so you can’t tell when the cookies are slightly golden brown.