Step 2

Make the Dough: Preheat the oven to 400°F. Set a fine-mesh sieve over a medium bowl. Add the flour, cocoa powder, cream of tartar, baking soda and salt to the sieve, and sift into the bowl.

Step 3

In the bowl of a stand mixer fitted with the paddle attachment, beat the butter and sugar together on medium-low speed to combine. Increase the speed to high and beat, scraping down the side and bottom of the bowl as needed, until light and creamy, about 1 minute. Reduce the speed to medium-low and add the eggs, one at a time, beating well on medium-high after each addition. Reduce the speed to medium-low and add the flour mixture, a little at a time, until there aren't any pockets of flour remaining. Reduce the speed to low, slowly add the chocolate chips, and mix until they are evenly dispersed, about 30 seconds. Scrape down the sides and bottom of the bowl.

Step 4

Make the Cinnamon-Chile Sugar: In a shallow soup bowl or on a dinner plate, stir together the sugar, cinnamon, and cayenne until thoroughly mixed. Set aside.

Step 5

Bake the Cookies: Line a sheet pan with parchment paper. Form 2 tablespoons of the cookie dough into a ball (about the size of a Ping-Pong ball) and roll it in the cinnamon-chile sugar topping. Repeat with the remaining dough. Place the balls on the parchment paper?lined sheet pan, spacing them 3 inches apart (you will need to bake the cookies in batches).

Step 6

Bake the cookies until they've flattened and are just set, 10 to 12 minutes, rotating the pan halfway through baking.

Step 7

Remove the pan from the oven, transfer the cookies to a wire rack and cool them completely before serving. Store the cookies in an airtight container for up to 3 days.