To make the pastry, mix together the flour, sugar, baking powder, salt and lemon zest until well combined. Add in the butter and rub into the flour with your finger tips until it resembles coarse crumbs the size of peas. Beat the egg in a small bowl and add to the flour mixture. Mix until it comes together to form a smooth dough. Wrap in plastic wrap and chill in the fridge for at least 1 hour.

For the Italian custard, heat the milk in a saucepan with the lemon zest and vanilla seeds and whole pod.

In the meantime, whisk the eggs, yolks, flour, sugar, and salt until completely smooth. The mixture will be somewhat thick. When the milk has warmed through, slowly pour and whisk into the egg mixture to temper. Pour the mixture back into the saucepan and set over medium-high heat. Cook, whisking constantly until the custard thickens, about 10 minutes. Remove from heat and let cool.

Preheat oven to 350 degrees F. Butter and flour a 9 or 10-inch tart pan with a removable bottom. Set aside.

Cut the chilled dough in half, transfer one half onto a lightly floured work surface and return the other half to the fridge. Roll out to a large circle and transfer to the prepared pan. Trim off any excess. Cover with a piece of parchment paper, fill with dry beans or pie weights and bake for 12 minutes. Remove from oven and let cool completely.

Fill the pie with the custard and smooth out into an even layer. Roll out the second half of dough and transfer on top of the pie. Trim off the edges and seal. Brush the top with egg wash and sprinkle with pine nuts. Bake until golden brown, 30 to 35 minutes. Remove from oven and let cool completely before dusting with powdered sugar, cutting and serving. Tart can also be chilled for several hours and dusted with sugar right before serving. Enjoy!