Preheat oven to 325 degrees. Line a baking sheet with parchment paper or spray with non-stick spray and set aside.
In a medium-sized bowl or zip-top bag whisk together all dry ingredients: flour, cocoa powder, baking powder, and salt; set aside.
In a large, microwave-safe bowl, combine the chocolate chips and butter. Heat them in the microwave on low-power for 20 second increments, mixing each time until butter and chocolate are melted. Whisk until smooth then whisk in the peppermint extract and both sugars and continue to whisk. Beat in eggs, one at a time. Add the milk and beat until incorporated.
Add the dry ingredients into the wet ingredients, and stir to combine with a spatula so you don't overmix. Fold in chocolate chunks mix together until just combined.
Use a large cookie scoop or 1/4 cup to measure batter, shape into uniform balls, and place onto the prepared baking sheet. *Batter will be sticky*
Bake for 7 minutes. Remove from oven and use the back of a measuring cup to slightly flatten, twisting as you press to ensure perfect circular cookie shape. Press additional chocolate chunks to the tops of each cookie. Return to oven and bake for another 5 minutes or until the cookies are set but a little gooey in the middle.
Allow cookies to cool on the tray for 10 minutes before removing. Cool cookies for 20 minutes before coating in white chocolate.