In a large mixing bowl, combine chilled unsalted butter, all-purpose flour, granulated sugar, a whole egg, an egg yolk, vanilla extract, and a pinch of salt. Mix until crumbly.

Wrap the pastry dough in plastic wrap and chill in the refrigerator for at least 30 minutes.

Heat whole milk in a saucepan until just simmering. In a separate bowl, whisk together egg yolks, sugar, cornstarch, and lemon zest. Gradually whisk in hot milk.

Return the mixture to the saucepan and cook on low heat until thickened, stirring constantly.

Remove from heat, stir in butter and vanilla extract until smooth. Cover with plastic wrap pressed against the surface to cool.

Preheat your oven to 350°F (175°C).

Roll out the chilled dough to about ¼ inch thick and fit it into the tart pan.

Prick the base with a fork and pour the cooled custard into the pastry shell.

Sprinkle with pine nuts or sliced almonds evenly.

Bake for 30-35 minutes until the pastry is golden brown and the custard is set.

Let it cool for 30 minutes, then transfer to a wire rack to cool completely.

Dust with powdered sugar before serving.