Instructions

• Preheat oven to 350°F (175°C). Line a baking sheet with parchment paper and set aside.
• If your egg is not at room temperature, remove it from the refrigerator now so it can warm while you work.
• In the bowl of a stand mixer fitted with the paddle attachment (or in a large bowl with a hand mixer), beat the 1 cup (2 sticks) butter and 1 cup powdered sugar until light and fluffy, about 2–3 minutes. Scrape down the sides of the bowl as needed.
• Add the egg, ½ teaspoon vanilla extract, and ¼ teaspoon lemon extract. Mix until just combined and smooth.
• Add the 2¼ cups flour and a pinch of salt. Mix on low speed just until the dough comes together and no large streaks of flour remain. Do not overmix.
• Cover the dough and refrigerate until firm, about 30–60 minutes.
• When the dough is chilled, place additional powdered sugar in a shallow bowl for rolling.
• Scoop tablespoons of dough and roll each into a ball. Roll each dough ball in the additional powdered sugar, then place them on the prepared baking sheet, leaving space between cookies for slight spreading.
• Using your thumb or the back of a teaspoon-sized measuring spoon, press a shallow well into the center of each dough ball to form a thumbprint.
• Spoon a small amount of lemon curd into each well (you will use less than half the jar spread across all cookies).
• Bake the cookies in the preheated oven for about 10 minutes, until the edges look set and there is slight browning along the bottom rims.
• Let the cookies cool on the baking sheet for a few minutes, then transfer them to a cooling rack to cool completely.
• Store fully cooled cookies in an airtight container in the refrigerator.