Combine softened butter, brown sugar & granulated sugar in a mixing bowl & beat well to combine.
Add in egg, egg yolk, vanilla & food color - mix well
Slowly beat in flour, cocoa powder, baking soda, baking powder & salt - mix until just combined
Fold in half of the white chocolate chips
Cover & chill in refrigerator overnight
The next day - preheat oven to 350 degrees
Line baking sheets with parchment paper & roll dough into balls- placing 1-1/2 inches apart on sheet
Bake 12-13 minutes
Immediately after removing from oven place additional white chocolate chips on the tops of the warm cookies before they cool
Transfer to a wire rack to cool & then store in an airtight container