In a bowl, combine cocoa powder, salt and baking soda then whisk and set aside.In a bowl fit with a mixer, cream butter on high for about 1 minute. Beat in brown sugar and granulated sugar on medium speed. Add milk, egg and vanilla extract while beating on medium low speed. Beat in food coloring and mix until combined. Slowly add dry ingredients to bowl and beat on low until dough forms. If desired, add additional food coloring then slowly beat in chocolate chips, reserving a few to top the cookies with after baking. Cover dough and chill for 1 hour or up to a few days. Allow dough to sit at room temperature for at least 35 minutes before baking in a 350 degree F oven. Line baking sheets with parchment paper and baking batch for about 10 minutes, give or take. Top with remaining chocolate chips, if desired.