For the lemon lover, delicate sandwich cookies that can either contain a gilding of jam or be made extra lemony with lemon buttercream or lemon curd, as pictured. — Rose Levy Beranbaum, The Baking Bible
Excerpted from The Baking Bible, © 2014 by Rose Levy Beranbaum. Reproduced by permission of Houghton Mifflin Harcourt. All rights reserved.
Special Equipment: 2¼-inch round cookie cutter and ¾-inch round cookie cutter
Store Airtight: room temperature, 1 day with buttercream (3 weeks with lemon curd, jam, or jelly); frozen, 6 months.
Food processor: Process the lemon zest with the sugar and salt until the zest is very fine.
Cut the butter into several pieces and add it with the motor running. Process until smooth and creamy. Add the egg and vanilla and process until incorporated, scraping down the sides of the bowl as needed. Add the flour and pulse in just until incorporated. The mixture will hold together if pinched.
Stand mixer: Soften the butter to 65 to 75 degrees F. Chop the lemon zest until very fine.
In the bowl of a stand mixer fitted with the flat beater, cream the sugar and butter on medium speed until fluffy. Add the lemon zest, egg, and vanilla and beat until blended. Scrape down the sides of the bowl.
In a small bowl, whisk together the flour and salt.
On low speed, gradually add the flour mixture to the butter mixture. Mix until incorporated and the dough just begins to come away from the sides of the bowl.
Scrape the mixture onto a large sheet of plastic wrap and use the wrap to press down on the dough, kneading it until it is smooth. Divide the dough into thirds, about 7.9 ounces each. Wrap each piece loosely with plastic wrap and press to flatten into discs. Rewrap tightly and place in a gallon-size re-sealable freezer bag. Refrigerate for 2 hours or up to 2 days to firm and give the dough a chance to absorb the moisture evenly, which will make rolling easier.
Twenty minutes or longer before baking, set an oven rack in the middle of the oven and preheat the oven to 350 degrees F.
Remove a dough disc from the refrigerator and set it on a lightly floured surface. Lightly flour the dough and cover it with plastic wrap. Let the dough soften for about 10 minutes, or until it is malleable enough to roll. Roll the dough ⅛ inch thick, moving it from time to time and adding more flour if necessary to keep it from sticking.
Cut out sixteen 2¼ inch cookies. Mark the centers of half the cookies with a needle or the tip of a knife. Use the ¾ inch round cutter or pastry tube to cut out the centers from the marked cookies. (If using a plastic cutter, or parchment-lined cookie sheet, it’s best to do this after placing the cookies on a cookie sheet.) Set the cookies a minimum of ½-inch apart on the cookie sheet.
Bake the cookies for 5 minutes. For even baking, rotate the cookie sheet halfway around. Continue baking for 5 to 7 minutes, or just until they begin to brown lightly. Set the cookie sheet on a wire rack and use a pancake turner to lift the cookies onto another wire rack. Cool completely.
While each batch of cookies is baking, roll the dough for the next batch. After the last batch is cut, knead together all the scraps and reroll them, chilling them first if necessary.
Using a small offset spatula or butter knife, spread the bottoms of the cookie halves (without the cutouts) with heaping ½ teaspoons of lemon buttercream or your favorite jam, jelly, or curd, and set the second set of cookies with the cutouts on top, bottom sides down, to create the sandwiches.
Beat the egg yolks in a medium bowl with a handheld mixer on high speed until light in color.
Have a 1-cup glass measure with a spout, lightly coated with nonstick cooking spray, ready.
In a small saucepan, preferably nonstick, using a silicone spatula, stir together the sugar and corn syrup until all of the sugar is moistened. Heat over medium-high, stirring constantly, until the sugar dissolves and the syrup begins to bubble around the edges. Stop stirring completely and continue cooking for a few minutes until the syrup comes to a rolling boil (the entire surface will be covered with large bubbles. At this point, the temperature of the syrup on an instant-read thermometer, if using, should read 238 degrees F). Immediately transfer the syrup to the glass measure to stop the cooking.
Beat the sugar syrup into the egg yolks in a steady stream. Do not let the syrup fall on the beaters or they will spin it onto the sides of the bowl. Continue beating on high speed for 5 minutes. Let it cool completely. To speed cooling, place the buttercream in an ice water bath or in the refrigerator and stir occasionally.
When the outside of the bowl feels cool, beat in the butter by the tablespoon on medium-high speed. The buttercream will not thicken until almost all of the butter has been added. Add the lemon zest, lemon juice, and vanilla and beat on low speed until incorporated. Raise the speed to high and beat until smooth and creamy. The buttercream may separate at first, but it will come together on beating.
Place the buttercream in an airtight container. Use it at once or set it aside for up to 4 hours. If keeping it longer than 4 hours, refrigerate it. Bring it to room temperature before using, to prevent curdling, and re-beat to restore the texture.