In a mixing bowl, combine all-purpose flour, powdered sugar, and salt. Whisk until well blended.

Add softened unsalted butter to the dry mixture. Work the butter into the flour until it resembles coarse crumbs.

Incorporate egg yolk into the butter-flour mixture, mixing gently until just combined.

Gradually add cold water, a tablespoon at a time, until the dough holds together when pressed.

Shape the dough into a disk, wrap it in plastic wrap, and refrigerate for at least 30 minutes.

Preheat your oven.

On a floured surface, roll out the chilled dough to approximately 1/8 inch thick.

Transfer the rolled dough to your tartlet pan, pressing it into the edges and trimming any overhanging edges.

Pierce the bottom of the crust with a fork to prevent bubbling.

Blind bake the crust until it is lightly golden.

Whisk together granulated sugar and eggs until smooth.

Slowly whisk in the freshly squeezed lemon juice and lemon zest.

Once the crust has cooled slightly, pour the lemon filling into the baked crusts, filling them evenly.

Bake the filled tartlets until the filling is just set.

Let the tartlets cool completely before removing them from the pan.