Preheat your oven to 350°F (175°C). In a large mixing bowl, combine flour, baking soda, salt, and cocoa powder. Whisk together and set aside.

In a mixing bowl, cream together butter, granulated sugar, and brown sugar until light and fluffy, about 3-5 minutes.

Beat in the eggs one at a time, followed by the vanilla extract, mixing until just combined.

Gradually fold the dry mixture into the wet mixture until no streaks of flour remain.

Portion out approximately 2 tablespoons of dough, roll into balls and place them on a lined baking sheet, spaced 2 inches apart.

Gently press M&Ms into the tops of the dough balls.

Bake for 9-11 minutes, until edges are set and tops are slightly cracked. Avoid overbaking.

Allow cookies to cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.