Preheat oven to 375°F (190°C). Line baking sheets with parchment paper.
In a medium bowl, whisk together flour, cocoa powder, baking soda, and salt. Set aside.
In a large bowl, cream together softened butter, granulated sugar, and brown sugar until light and fluffy.
Beat in eggs one at a time, then stir in vanilla extract.
Gradually add the dry ingredients to the wet ingredients, alternating with the milk, beginning and ending with the dry ingredients. Mix until just combined.
Stir in the chocolate chips.
Drop rounded tablespoons of dough onto the prepared baking sheets.
Bake for 10-12 minutes, or until the edges are set and the centers are still slightly soft.
Let the cookies cool on the baking sheets for a few minutes before transferring them to a wire rack to cool completely.
Notes
These cookies are best enjoyed warm with a glass of milk or another cup of hot chocolate!