1-First Step: Start by making the tart crust. In a food processor, pulse together 1 1/2 cups all-purpose flour, 1/4 cup powdered sugar, and 1/2 cup cold unsalted butter (cubed) until the mixture resembles coarse crumbs. This should only take about 30 seconds of pulsing. If you don’t have a food processor, you can use a pastry cutter or your fingers to work the butter into the flour until it looks like breadcrumbs.

2-Second Step: Add 1 egg yolk and 2 tablespoons cold water to the flour mixture. Pulse again just until the dough begins to clump together. Be careful not to overmix, as this can make the crust tough. The dough should hold together when pinched between your fingers. If it’s still too crumbly, add another teaspoon of cold water and pulse again briefly.

3-Third Step: Turn the dough out onto a lightly floured surface and gently knead it just until it comes together in a ball. Flatten into a disk, wrap in plastic wrap, and refrigerate for at least 30 minutes. This resting period is crucial as it allows the gluten to relax, preventing shrinkage during baking. For best results, chill the dough overnight if time permits.

4-Fourth Step: On a lightly floured surface, roll out the chilled dough to a 11-inch circle, about 1/8-inch thick. Carefully transfer the dough to a 9-inch tart pan with a removable bottom. Gently press the dough into the bottom and up the sides of the pan, being careful not to stretch it. Trim any excess dough by rolling your rolling pin over the top of the pan. Freeze the lined tart pan for 15 minutes to firm up the dough again.

5-Fifth Step: Preheat your oven to 375°F (190°C). Line the chilled crust with parchment paper or aluminum foil, then fill it with pie weights, dried beans, or rice. This technique, called blind baking, prevents the crust from puffing up or shrinking. Bake for 15-20 minutes until the edges are golden. Remove the weights and paper, then bake for an additional 8-10 minutes until the bottom is fully cooked and golden. Let the crust cool completely before adding the filling. This step ensures your crisp shortbread crust won’t become soggy when filled.

6-Sixth Step: While the crust cools, prepare the lemon curd filling. In a medium saucepan, whisk together 1 cup fresh lemon juice, zest of 3 lemons, 1 cup granulated sugar, 3 large eggs, and 1 additional egg yolk. Place the saucepan over medium heat and stir constantly with a heatproof spatula or wooden spoon. For a silky smooth texture, make sure all ingredients are at room temperature before beginning.

7-Seventh Step: Continue cooking the mixture, stirring constantly, until it thickens enough to coat the back of a spoon and reaches 160°F (71°C). This usually takes about 8-10 minutes. The mixture should bubble gently around the edges but not boil vigorously. This cooking time is essential to properly cook the eggs and activate the thickening properties. If you’re concerned about curdling, you can temper the eggs by whisking a small amount of the warm lemon juice into them before combining all ingredients.

8-Eighth Step: Remove the saucepan from heat and immediately add 1/2 cup unsalted butter (cubed), one piece at a time. Stir until each piece melts before adding the next. If using, add 1 teaspoon vanilla extract at this stage. For an ultra-smooth filling, strain the mixture through a fine-mesh sieve into a clean bowl to remove any bits of cooked egg. This ensures your lemon curd will be perfectly silky.

9-Ninth Step: Pour the warm lemon curd into the cooled tart crust. Use an offset spatula to spread it evenly and smooth the top. Place the tart in the refrigerator and chill for at least 4 hours, or until completely set. For the best results, chill overnight to allow the flavors to meld properly. The lemon filling will firm up as it cools, making it easier to slice cleanly.

10-Final Step: Once fully chilled, remove the tart from the refrigerator. If desired, garnish with fresh berries, a dusting of powdered sugar, or a dollop of whipped cream just before serving. To slice, run a thin knife between the crust and the pan side to loosen, then remove the pan rim. Slice with a sharp knife, wiping the blade clean between cuts for picture-perfect slices. Serve chilled and enjoy the perfect balance of crisp crust and creamy lemon filling!