Step 1

Combine flour, baking soda, salt, and cocoa powder in a bowl. Whisk together, and set aside.

Step 2

With a mixer, cream the butter and sugars together until light and fluffy — at least 3-5 minutes. Add the egg, scraping down sides of the mixing bowl as needed. Add the vanilla extract, mix, then add the milk and mix to combine.

Step 3

Add the dry ingredients and mix gently until just coming together.

Step 4

The dough will be very firm, so gently fold in the dark chocolate chips.

Step 5

Chill the dough for 30 minutes.

Step 6

Preheat the oven to 350 F. Using a small cookie scoop, or a spoon, form 1/8 cup balls of dough. Flatten slightly.

Step 7

The cookies will not spread very much during baking, so set them 1 to 2 inches apart on a lined cookie sheet. Cook for 9-11 minutes. They will not look done, but the edges will be set.

Step 8

Remove from the oven and let cool for a few minutes on the cookie sheet before moving to a cooling rack.