Plan on time for chilling the cookie dough.
In a medium bowl, whisk together flour, cocoa powder, baking powder, and salt
In a large mixing bowl, cream together the softened butter and sugar until light and fluffy, mix for about three minutes. You can use a stand mixer, or a handheld electric mixer.
Set the mixer on medium speed and mix in the eggs one at a time, scraping down the sides of the bowl in between additions
Add milk, food coloring, and vanilla then mix at medium speed until well combined. Scrape the bowl, and then mix again just to get everything combined.
Gradually add the flour mixture while mixing on medium-low speed, scraping down the sides of the bowl in between additions. You will have a nice smooth dough when mixed.
Cover the bowl with plastic wrap and chill for 30 minutes, or up to one day. You can transfer the dough into a smaller bowl and cover it with plastic wrap.
When ready to bake, heat the oven to 350° F., and prepare two baking pans with parchment or a silicone baking mat.
Pour the powdered sugar into a small bowl.
Using a cookie scoop or a tablespoon, scoop the dough and roll it into balls then immediately roll in the powdered sugar
Bake for 12-14 minutes or until cookies are set and the tops are cracked. Remove the cookies from the oven and cool them on the baking sheet for 5 minutes then transfer them to a wire rack to cool completely.
Store the cookies in an airtight container for several days.