Preheat oven to 350 degrees and line cookie sheets with parchment paper or cookie sheet liners.
Cream together the butter, sugar, eggs and milk until well combined.
In a separate bowl, stir together the dry ingredients: flour, cocoa, baking powder and salt. Add the flour mixture to the wet ingredients and mix to combine. Dough should be fairly stiff - if it's quite sticky you can mix in another few tablespoons of flour.
Liberally flour your countertop. Scoop out about 1/3 of the cookie dough. Flour a rolling pin and roll the dough to just under 3/8 inch thick. Try not to use too much flour on top of the dough as it may be visible after baking.
Use a cookie cutter to cut out cookies and transfer them to a baking sheet.
Bake for 9-10 minutes until the edges of the cookies just feel set and the tops are barely cracked.
Remove cookies to a wire rack and cool completely before frosting. Repeat with remaining cookie dough.