Hot Chocolate Cookies with Marshmallow Fluff

Place the racks in upper and lower thirds of the oven and preheat to 350 degrees. Sift the flour, cocoa powder, cornstarch, nonfat dry milk powder, baking powder, cinnamon, and baking soda into a medium bowl.

Using an electric or stand mixer on medium-high speed, beat the brown sugar, butter, and salt in a large bowl until light and fluffy, about 3 minutes. Add the eggs one at a time, beating after each addition until combined before adding the next, then beat in the vanilla extract. Reduce the speed to low and add half of the dry ingredients; beat just until combined. Add the remaining dry ingredients and beat until no streaks remain. Add the milk chocolate and gently fold it in with a rubber spatula just until evenly distributed.

Portion out 18 cookies (the dough will be very sticky), dividing between 2 parchment-lined baking sheets and spacing at least 2" apart. Dollop about ½ teaspoon marshmallow creme onto each cookie; smooth and swirl into and over the dough as desired. Bake the cookies, rotating the baking sheets top to bottom and front to back halfway through, until the cookies spread out and are slightly puffed, about 10–12 minutes. Remove from the oven.

Let the cookies cool on the baking sheets, then transfer them to a wire rack.

Bon Appetit’s tips for the best hot chocolate cookies:

• Keep it room temperature. This cookie dough bakes up best at room temperature, but you can still make it ahead. Let it rest up to 30 minutes after mixing or refrigerate for up to 24 hours, then bring to room temperature before continuing (the marshmallow fluff will slide off cold dough).
• How to choose chocolate: We love high-quality milk chocolate for the chunks in these cookies; they offer richness and a creamy flavor reminiscent of hot cocoa. Look for bars with a cacao content between 35-45% (traditional milk chocolate bars range around 25% chocolate). For bolder chocolate flavor, you can substitute semi- or bittersweet chocolate.
• Don’t sweat the swirl. There is no such thing as perfection with the marshmallow swirl; each cookie will look different, and that’s okay!
• Round ’em up. We can’t all be perfect and these cookies may emerge from the oven a little misshapen. Grab a ring cutter or a glass and put it into orbit around the edge of the cookies to hone their shape.
• Beware of layering. The marshmallow makes the tops of these cookies somewhat sticky, so try to avoid stacking them lest you mar all your beautiful swirls.