Ingredients
Method
Step-by-Step
- Heat the oven to 350°F (175°C) and line two baking sheets with parchment paper.
- Beat the softened butter and powdered sugar until smooth and creamy, about 2 minutes. Mix in the vanilla extract, finely grated lemon zest, and finely grated lime zest.
- Add the flour and salt gradually, mixing only until a soft dough forms. Avoid overmixing so the finished shortbread stays tender.
- Chill the dough for about 30 minutes. For especially clean thumbprints, shape the cookies first and chill the filled-out cookie rounds for an additional 10–15 minutes before baking.
- Scoop approximately 1 tablespoon of dough for each cookie and roll it into a ball. Arrange the balls about 2 inches apart on the prepared baking sheets.
- Press a thumb or the rounded end of a 1/2-teaspoon measure into the center of each dough ball to create a shallow well. If the dough cracks slightly around the edges, gently smooth it with your fingertips.
- Bake for 12–14 minutes, until the edges are set and only lightly golden. The shortbread should remain fairly pale rather than becoming deeply browned.
- If the centers puff during baking, gently press them down again while the cookies are warm. Cool the cookies on the baking sheet for 5 minutes, then transfer them to a rack.
- Fill each cooled cookie with approximately 1 teaspoon of lemon curd, lime curd, or lemon-lime curd. Let the curd set slightly before adding the glaze, if using.
- For the optional glaze, stir the powdered sugar with 1–2 tablespoons of fresh lemon or lime juice until smooth and drizzleable. Drizzle over the cookies and decorate with a little extra citrus zest.
Notes
Use finely grated zest instead of bottled citrus juice in the dough because zest gives concentrated flavor without making the shortbread wet. If the curd is soft, add it after baking to prevent bubbling or excessive spreading. Store finished cookies in a covered container, with parchment between layers if needed.