In a food processor, combine 1 ½ cups all-purpose flour, ½ cup granulated sugar, and a pinch of salt. Add ½ cup unsalted butter, cut into pieces, and pulse until the mixture resembles coarse crumbs with some pea-sized bits remaining.

In a small bowl, whisk together 1 egg yolk, 2 tablespoons ice cold water, and 1 teaspoon vanilla extract. Gradually add this mixture to the flour blend in the food processor, pulsing until large clumps form.

Shape the dough into a disk, wrap it tightly in plastic wrap, and refrigerate for at least 1 hour or up to 3 days.

After chilling, lightly flour your work surface and roll out the dough to about ¼ inch thick and slightly larger than a 9-inch tart shell. Carefully press the rolled dough into the tart pan, ensuring it hugs the sides well.

Preheat your oven to 375°F (191°C). Prick the bottom of the tart crust with a fork, then line it with parchment paper and fill with baking beads or dried beans. Bake for 15 minutes, remove the lining, and bake for another 5 minutes until lightly golden.

In a heatproof bowl set over simmering water, whisk together 4 egg yolks, ½ cup granulated sugar, ½ cup lemon juice, 2 teaspoons lemon zest, and a pinch of sea salt. Stir continuously for about 10 minutes until the mixture thickens.

Once thickened, remove the bowl from heat and whisk in 4 tablespoons of room temperature unsalted butter and 4 ounces of finely chopped white chocolate. Stir until smooth.

Pour the lemon curd carefully into the cooled tart shell. Bake in the oven for 10-12 minutes, until the curd is just set but still jiggles slightly in the center.

Allow the tart to cool to room temperature, then refrigerate for at least 4 hours or preferably overnight.