Timetable: 20 minutes (does not include dough prep)/Group size: medium-largeYields: 8 dozen cookiesToolbox:
5 1/3 cups all-purpose flour
1 tsp baking powder
1 tsp salt
1 lb (2 cups or 4 sticks) unsalted margarine, at room temperature
2 cups granulated sugar
1 tbsp pure vanilla extract
2 large eggs at room temperature
½ cup unsweetened cocoa powder
Prep:Sift the flour, baking powder, and salt. Set aside.In a large bowl, using an electric mixer, beat the butter and sugar together until light and fluffy.Beat in the eggs, one at a time, and then add the vanilla extract.Add the flour mixture and mix to combine.Divide the dough in half.Knead ½ cup of cocoa into one portion of the dough. (If you find that the dough is too tough, add one egg white.)Form the dough into a somewhat rectangular shape.Wrap the dough in a plastic wrapper, and then put in the fridge for at least 15 minutes (You can leave it overnight.)
Make eight small square logs from each dough: Divide the vanilla and chocolate doughs each into 2 pieces. Roll each piece into a 6-inch log, then press each log into a 1½-inch-thick square shape. Quarter the squared-off logs lengthwise with a chef’s knife.
Assemble the logs into a checkerboard pattern: Layer 2 strips of vanilla and 2 strips of chocolate dough into a checkerboard pattern, and squeeze together gently to adhere. Repeat with the remaining strips to make 4 6-inch checkerboard logs. Wrap the dough tightly in plastic wrap and refrigerate until firm, about 2 hours.
Carefully slice the chilled log: Preheat oven to 350. Slice each log into ¼-inch-thick cookies and place on an oiled baking sheet. Bake the cookies, in batches, for about 12 minutes until firm and golden brown on the bottom. Don’t let them bake for too long, or the color contrast between the chocolate and vanilla dough will be lost.