In a stand mixer, cream the butter for 20 seconds. Add both of the sugars, and cream until light and fluffy, about 2 minutes.
1/2 cup butter, 1/2 cup granulated sugar, 1/2 cup brown sugar
Beat in the egg and vanilla, until well combined.
1 whole large egg, 1 teaspoon vanilla extract
Mix in the flour, cocoa powder, baking soda and salt. The dough should be pretty thick. Using a spatula, mix in the milk. Start with 1 Tablespoon, if you live in a dry climate or added a little bit too much flour, you will need to add a 2nd Tablespoon. You don't want to the dough sticky or too wet.
1 cup all-purpose flour, 1/2 cup cocoa powder, 1 teaspoon baking soda, 1/4 teaspoon salt, 1-2 Tablespoons milk
Stir in 1 cup of mini M&M's.
1 1/4 cup mini M&M's
Chill the dough for at least 30 minutes. The longer it chills, the thicker the cookies will be!
Preheat oven to 350º F. Scoop golf ball sized balls of dough into a baking sheet. Press a few mini M&M's into the top of each ball of dough.
Bake for 9-10 minutes. The cookies will be done on the edges, but appear underdone in the center. Let the cookies cool on a baking sheet for 5 minutes before removing to a wire rack.
Store in an air tight container for up to a week
Video
Notes
Start with 1 Tablespoon of milk, if you live in a dry climate or added a little bit too much flour, you will need to add a 2nd Tablespoon. You don't want to the dough sticky or too wet, just to come together like a normal cookie dough.Slightly adapted from Sally's Baking Addiction