Prepare pastry:

1. Roll out the pie dough to an 11″ circle and line a 9” pie plate with the pastry, crimping the edges as desired. Place in the freezer to firm up for 10-20 minutes.
2. Preheat oven to 375ºF and place one oven rack in the second to lowest spot and one in the middle.
3. Line the pie dough with a parchment round piece of paper and then add pie weights to fill (such as dry rice, bean or lentils), making sure to push the pie weights to the edges. Bake for 20 minutes on the lower rack, then remove from the oven and remove the parchment and pie weights. Return to the oven and bake for an additional 5-10 minutes until the pastry is fully baked through.
4. While the crust is still hot, crack one egg and separate the yolk from the white. Set the yolk aside. Whisk together the egg white with a teaspoon of water and brush a thin layer of the mixture on the hot pie crust all over. The heat from the crust should turn the brushed egg white and cook it. If your pie has cooled down too quickly, you can place it back in the oven for a few minutes until the egg white is set. Set aside the prepared crust until ready to use.
5. Lower the heat to 325º.

To make the filling:

1. Whisk together the granulated sugar, cornstarch and salt in a bowl. Add in the remaining 4 eggs, the leftover egg yolk, and the lemon juice, and whisk together. 
2. Heat the milk in a medium pot over medium heat until small bubbles form along the edges, about 120ºF.
3. Next, temper the egg mixture: Slowly pour in 1 cup of the warmed milk to the eggs, while gently whisking. Then, pour the whole egg mixture slowly back into the pot of milk while gently whisking. Continue to cook the mixture for 2-3 minutes, until the mixture has just barely thickened and reached 170-180ºF. To double-check the custard has formed, take a wooden spoon and coat it with the milk. Draw a horizontal line on the back of the spoon with your finger. If the line “holds” then your custard is set. If the line collapses right away, the custard needs another minute or so. However do not bring the mixture to a boil, this will overcook the custard.
4. Strain the mixture to catch any bits of cooked eggs. Add in the lemon extract, vanilla extract and the zest and then slowly pour the filling into the baked crust.

Bake the pie:

1. Place the pie onto your oven’s middle rack and bake it for 50-55 minutes, or until the custard has puffed up and set nearly throughout, but still slightly wobbly in the middle. The pie should have a temperature of 190ºF in the middle.
2. Remove the pie from the oven, and place it on a rack to cool.
3. Once the pie has come to room temperature, move the pie to the refrigerator to finish setting up, at least 4 hours.

Make the Whipped Cream:

1. Add all the ingredients to the bowl of an electric mixer and whip on medium speed until the cream has reached soft stiff peaks, about 2 minutes. Keep a close eye though because it will go from perfectly whipped to over-whipped in a matter of seconds.

Serve the pie chilled with a dollop of whipped cream.