Sugar cookies are great, but chocolate sugar cookies are the bee’s knees. These little circles are full of chocolate flavor, with crisp edges and a tender center.
Three variations: Cardamom Chocolate Sugar Cookies—Add 1 teaspoon of ground cardamom to the sugar used for rolling. Chocolate Mint Sugar Cookies—Add 1 teaspoon of mint extract along with the vanilla. Double Chocolate Sugar Cookies—Add 3 ounces (85 grams) of chopped semisweet or bittersweet chocolate after mixing in the dry ingredients.
Adjust an oven rack to the middle of the oven. Heat the oven to 350°F (180°C). Line three sheet pans with parchment paper.
In a small bowl, combine the flour, cocoa powder, baking soda, and salt.
In the bowl of a stand mixer fitted with a paddle, beat the butter on medium speed until creamy, about 1 minute. Add 1 3/4 cups (350 grams) of the sugar, and beat again until light and fluffy, 2 to 3 minutes. Add the egg, yolk, and vanilla, and beat on low speed until combined. Add the flour mixture and beat again on low speed until combined.
Place the remaining 1/2 cup (100 grams) of sugar in a medium bowl.
Scoop the dough into 1 1/2-ounce (45-gram) portions (2 tablespoons). Roll each ball in the sugar. Place 8 cookies on each sheet pan.
Bake one pan at a time, rotating halfway through baking. Bake until the sides are set and the top begins to crackle, 12 to 14 minutes.
Transfer the sheet pan to a wire rack and let the cookies cool for 5 to 10 minutes on the pan, then remove the cookies and let them cool completely on the wire rack. Store cookies in an airtight container at room temperature for up to 3 days.