Looking for the ultimate cookie to leave for Santa this year? Look no further than these rich, fudgy cookies studded with chocolate chunks and melty marshmallows and dusted with crunchy peppermint candies. They’re like a mug of holiday hot chocolate in cookie form! Pro tip: For uniform cookies worthy of Saint Nick, use a 1½-inch cookie scoop when portioning out your dough.
In a large bowl, sift the flour with the cocoa powder, baking soda, baking powder and salt.
In the bowl of a stand mixer fitted with the paddle attachment, or using a hand mixer and a large bowl, cream the butter with both sugars on medium-high speed until light and fluffy, 3 to 5 minutes. Reduce the speed to low and beat in the eggs, vanilla extract and peppermint extract until just combined. On low speed, gradually add the dry ingredients and beat until just incorporated. Add the chocolate chunks and mini marshmallows and beat on low until just combined. Cover the bowl and refrigerate for at least 1 hour or overnight.
Preheat the oven to 350° and line two rimmed baking sheets with parchment paper. Form the dough into approximately 1½-inch balls and set on the baking sheets roughly 2 inches apart. Use the palm of your hand to gently flatten the cookies. Bake the cookies until the centers are just set, about 10 minutes. Remove from the oven and immediately sprinkle with the crushed peppermint candies. Let the baking sheets cool on wire racks. Repeat with the remaining dough. Serve warm or at room temperature.
MAKE AHEAD The unbaked cookie dough can be refrigerated overnight. The cookies can be baked and stored in an airtight container at room temperature for up to 3 days.