THE BEST CHOCOLATE BUTTER COOKIES

Steps:

• Melt 4 tablespoons of the butter in medium saucepan over medium heat. Add cocoa and expresso powders; stir until mixture forms a smooth paste. Set aside to cool, about 15 minutes.
• In bowl of a stand mixer fitted with paddle attachment, mix remaining 16 tablespoons butter, sugar, salt, and cooled cocoa mixture on high speed until well combined and fluffy, about 1 minute, scraping sides of mixing bowl once or twice with rubber spatula. Add yolks and vanilla and mix on medium speed until thoroughly combined, about 30 seconds. Scrape sides of bowl. With mixer running on low, add flour in 3 additions, waiting until each addition is incorporated before adding net and scraping bowl after each addition. Continue to mix until dough forms cohesive ball, about 5 seconds. Turn dough onto work surface; divide into 3 4-inch disks. Wrap each disk in plastic wrap and refrigerate until dough is firm yet malleable, 45 to 60 minutes.
• Adjust oven rack to middle position and preheat oven to 375 degrees.
• Roll 1 dough disk between 2 large sheets of parchment paper to even thickness of 3/16-inch. (If dough becomes soft and sticky, slide rolled dough on parchment onto baking sheet and rechill until firm, about 10 minutes.) Peel parchment from one side of dough and cut into desired shapes using cookie cutter(s) Use a thin metal spatula to transfer the cookie shapes to the prepared baking sheet, spacing them about 1 inch apart. Gather dough scraps and chill to use again.
• Bake about 10-12 minutes. The cookies will offer slight resistance to the touch when done. If they yield too easily, they are underdone. If they begin to darken on edges they have overbaked. Rotate the baking sheet halfway through baking time. Cool for 5 minutes, then, using the spatula, transfer them to wire rack and cool completely,.
• VARIATIONS:.
• Instead of forming dough into disks, you may form it into logs about 2 inches in diameter and 12 inches long. Wrap with plastic wrap to make a nice cylinder. Chill until very firm; then simply slice dough into 1/4-inch slices as you would refrigerator cookies. Continue as above.
• Cookies may be served plain or dusted with sifted powdered sugar. The logs of dough may be rolled in sanding sugar or chopped nuts just before slicing.
• Make a glaze by melting 4 ounces bittersweet chocolate with 4 tablespoons unsalted butter and whisk until smooth. Add 2 tablespoons corn syrup and 1 teaspoon vanilla land mix until smooth and shiny. Use back of spoon to spread scant teaspoon glaze to edge of each cookies. It may be necessary to reheat glaze to keep it spreadable. Allow glazed cookie s to dry at least 20 minutes.
• Mexican Chocoate Butter Cookies: Combine 1/2 cup sliced almonds, 1 teaspoon ground cinnamon, and 1/8 teaspoon cayenne in a medium skillet. Toast until fragrant, about 3 minutes. Allow to cool; then process in a food processor until very fine, about 15 seconds. Follow recipe above for Chocolate Butter Cookies, whisking nut mixture into flour before adding flour to dough in step 2. Proceed with recipe. Roll dough into log and roll the log in 1/2 cup sanding sugar.
• Glazed Chocolate-Mint Cookies: Follow recipe above for Chocolate Butter Cookies, replacing the vanilla extract with 2 teaspoons mint extract. It is nice to melt 1 cup white chocolate chips and drizzle over glazed cookies. Let dry at least 20 minutes before serving.