Chocolate Sugar Cookies

I have to admit that while I have yet to bake out of Sara Kieffer's new and very popular cookbook, 100 Cookies, I have been very lucky to be surrounded by people who do. This week's confection comes from my eldest son and eldest granddaughter, who is an early bloomer when it comes to loving chocolate. My mom should be very proud, because while neither my brother nor I inherited her deep abiding love of chocolate, it appears that her genes have been indeed passed on. These are #8 in the book and very good. 2 cups (284 grams) all-purpose flour 1/2 cup (50 grams) Dutch-process cocoa powder 3/4 teaspoon baking soda 3/4 teaspoon salt 1 cup (2 sticks or 227 grams) unsalted butter, at room temperature 1 3/4 cups (350 grams) granulated sugar, plus 1/2 cup (100 grams) for rolling 1 large egg plus 1 large yolk 2 teaspoons pure vanilla extract 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 day (I recommend popping them in the freezer right away myself.