Preheat your oven to 400°F (204°C) and line two baking sheets with parchment paper.

In a stand mixer with the paddle attachment, cream together the cold butter, light brown sugar, and granulated sugar until smooth.

Incorporate the large egg and egg yolk, followed by vanilla and peppermint extracts, mixing until well combined.

In a separate bowl, whisk together the flour, cocoa powder, salt, baking powder, and baking soda.

Gradually add the dry ingredients to the wet mixture, mixing on low speed until just combined.

Fold in the semi-sweet chocolate chunks, milk chocolate chips, and white chocolate chips.

Shape the dough into 8 large balls and place them on the prepared baking sheets.

Bake for 12-13 minutes, until the edges are set.

Sprinkle the tops of the cookies with crushed peppermint candies immediately after baking, pressing lightly.

Cool the cookies on the baking sheet for 10 minutes before transferring to a wire rack.