• On a lightly floured surface, roll cold pie dough into a 12-inch/30cm circle. Drape it into a 9-inch pie plate. Cut off any excess dough around the pie dish to make it even, but leave a bit of an overhang. Roll the overhanging dough under the edge to make a thick border.
• Flute the edges, then chill the pastry for at least 20 minutes while preheating the oven to 425°F (220°C)
• Prick the bottom of the pie crust all over with a fork. Line the crust with parchment paper and fill it with pie weights. Bake for 10-15 minutes until the edges are lightly browned.
• Remove it from the oven and lift off the parchment paper and weights. Lower the oven temperature to 375°F (190°C).
• Dock the pastry with a fork. Return the pastry to the oven for 15-20 minutes until it's golden brown and crisp. Let the pie shell cool completely. 

Filling

• In a medium bowl, whisk together egg yolks and sugar until combined. Set this aside.
• In a medium saucepan combine milk, cream, cornstarch, lemon juice, lemon zest, vanilla and salt. Whisk it all together until smooth. Place the mixture on the stove over medium-high heat and keep whisking as it warms.
• Once the mixture is at a simmer, remove the mixture from the stove and drizzle it slowly into the egg yolk mixture, whisking the egg yolks as you do.
• Once it's all incorporated in the egg yolks, tip everything back into the saucepan and place it over medium heat. Continually whisk as the mixture begins to bubble and thicken so that the milk doesn't burn at the bottom of the saucepan.
• Once boiling, let it bubble while whisking for a full minute until nice and thick. (this step is important, or the filling won't set.) Remove it from the heat and whisk through the cold butter.
• Push the lemon mixture through a fine mesh strainer to remove the lemon zest for an extra smooth filling. Pour the filling into the pie crust. You can cover the lemon custard filling with plastic wrap and gently press it onto the filling. This stops a skin from forming, but it's not necessary since it will be covered later with cream.
• Let the pie cool to room temperature, then chill it in the refrigerator for at least 4 hours until firm.

Whipped cream

• When ready to serve, layer whipped cream on top of the pie.
• In a bowl combine 3/4 cup heavy cream, a tablespoon of powdered sugar, and a teaspoon of vanilla paste or extract. Whip it with an electric mixer on medium-high speed until soft peaks form but take care not to over-whip it. Dollop the cream or pipe it around the edge of the pie.