STRIPED SHORTBREAD COOKIES RECIPES

Steps:

• Whisk 1? cups flour and ¾ tsp. salt in a medium bowl. Whisk cocoa powder, remaining 1 cup flour, and remaining ¾ tsp. salt in another medium bowl. These are the bases for your chocolate and vanilla doughs.
• Beat butter, granulated sugar, and powdered sugar in the bowl of a stand mixer on medium-high speed until light and fluffy, about 4 minutes. Add egg yolk and vanilla and beat until smooth. Divide mixture between the 2 bowls of dry ingredients (about 1 cup in each). Scrape vanilla mixture back into stand mixer bowl (save the mixing bowl) and beat on low speed just until combined. Return to reserved bowl. Repeat process with chocolate mixture.
• Arrange 2 large sheets of parchment paper on a work surface. Dollop one-quarter of chocolate dough in the center of each sheet and pat into rough 6x2" rectangles. Dollop one-quarter of vanilla dough on top of each chocolate slab and pat into rectangles the same size and shape so that you have 2 layers each. Repeat entire process so you have 4 alternating layers. Tightly press stacked dough into cylinders about 1½" wide and 8" long, using the parchment to help you. Wrap logs in plastic wrap and chill until very firm, at least 2 hours.
• Place racks in upper and lower thirds of oven; preheat to 350°. Working one at a time, unwrap dough and brush with egg. Carefully sprinkle surface with sanding sugar and roll logs in sugar to coat well (really press dough into sugar so it sticks). Slice into rounds a generous ¼" thick, rotating after every few cuts to keep slices round. Arrange cookies on parchment-lined baking sheets, spacing 2" apart. Bake, rotating baking sheets top to bottom and front to back halfway through, until edges are just set, 12–14 minutes. Let cool on baking sheets.
• Do Ahead: Dough can be made 3 days ahead; keep chilled. Cookies can be baked 5 days ahead; store airtight at room temperature.

Steps:

• Whisk together flour and salt in a small bowl. Beat butter, powdered sugar, and granulated sugar with a stand mixer fitted with a paddle attachment on medium speed until light and fluffy, about 3 minutes. Add vanilla extract, and beat until blended, about 10 seconds. Reduce speed to low, and gradually add flour mixture, one-third at a time, beating just until blended after each addition, about 1 minute.
• Turn dough out onto a lightly floured surface, and knead a few times until dough comes together. Halve dough, and set 1 portion aside for plain dough. Return remaining dough to mixer, and add cocoa, beating on medium speed until blended, about 2 minutes. Divide chocolate dough and plain dough each into thirds, and roll each piece into a 15-inch rope. Stack ropes alternately on top of each other, flattening each slightly into a strip to cover previous layer. Roll dough into an even log by gently pushing each end toward center of log and rolling as needed. Wrap in plastic wrap, and refrigerate 2 hours. 
• Preheat oven to 350°F. Line 2 baking sheets with parchment paper. Trim log so ends are flat, and slice half of log crosswise into ¼-inch-thick slices. Arrange cookies on prepared baking sheets, spacing them 2 inches apart. Place remaining unsliced log of dough and 1 baking sheet of cookies in refrigerator.
• Bake remaining baking sheet of cookies in preheated oven until set and lightly golden on bottoms, about 14 minutes, rotating baking sheet from front to back halfway through bake time. Let cool on baking sheet 5 minutes; transfer cookies to a wire rack to cool completely, about 30 minutes. Meanwhile, bake remaining baking sheet of cookies as directed. Repeat slicing and baking procedure with remaining dough log in refrigerator, lining baking sheets with a new sheet of parchment paper for each batch. Reserve baking sheets, and line each with a new sheet of parchment paper. 
• Place sprinkles in small bowls. Melt semisweet chocolate chips according to package directions, and stir in oil. To decorate, dip edge of each cookie in chocolate mixture, and top immediately with sprinkles. Place on prepared baking sheets, and let stand until chocolate sets, about 30 minutes. Store in an airtight container until ready to serve.