In a large mixing bowl, combine all-purpose flour, granulated sugar, and salt, whisking them together until well blended. Cut in cold unsalted butter until the mixture resembles coarse crumbs. Gradually add egg yolk and cold water, mixing until the dough forms. Wrap in plastic wrap and chill for 20–30 minutes.

Preheat your oven to 350°F (175°C). Roll out the chilled dough on a floured surface to fit your pie dish. Prick the bottom with a fork and bake for 12–15 minutes until lightly golden. Cool completely.

In a medium saucepan, whisk together granulated sugar, cornstarch, lemon zest, and egg yolks until smooth. Gradually add in whole milk and stir over medium heat for about 5–7 minutes until thickened. Remove from heat and stir in fresh lemon juice, unsalted butter, and vanilla extract until smooth.

Pour the custard filling into the cooled crust, smoothing the top. Bake for 25–30 minutes until set with a slight jiggle in the center.

Remove from the oven, allow to cool completely on a wire rack. Dust with powdered sugar and slice into wedges for serving.