Preheat the oven to 350˚ Fahrenheit. Line 2 baking sheets with parchment paper. Place flour, salt, and baking powder in a medium bowl and set aside. In the bowl of an electric mixer, combine the butter and sugar. Beat together on medium-high speed until light and fluffy, 2-3 minutes. Beat in the eggs one at a time, until incorporated. Be sure to scrape down the bowl as needed. Stir in vanilla extract. Add the cocoa powder until well blended. Add the flour mixture to the mixing bowl and mix on low speed just until incorporated. Fold in the milk chocolate chips with a spatula. Transfer the dough to a clean work surface and press together by hand ensuring all ingredients are well combined. Divide the dough into 4 ounce portions (You'll end up with about 11 cookies). You can also divide into 12 equal portions using a bench scraper. Roll each portion of dough into a ball (this is messy. Just letting you know) and flatten slightly. Place on the prepared baking sheets, planets (far) apart. Bake for about 14-16 minutes, rotating the pans halfway through for even baking. Allow the cookies cool on the baking sheets for about 5-10 minutes, then transfer to a wire rack to cool completely.