In a bowl, whisk together the egg yolk, heavy cream, and vanilla.

In a food processor, combine the flour, confectioners sugar, and salt.

Add the cubed butter to the food processor and pulse until the mixture resembles coarse crumbs.

Add the egg yolk mixture to the food processor and pulse until a dough forms.

Form the dough into a disk and place it into a Ziploc bag. Chill the dough in the refrigerator for at least 1 hour.

Roll the dough out into an 11-inch circle.

Place the dough into a tart pan that is on a sheet pan and gently push it into the corners.

Cut off any extra dough from the top of the pan.

Loosely wrap the tart shell in plastic and put it in the freezer for 30 minutes.

Preheat the oven to 350 degrees Fahrenheit.

Line the tart shell with 2 layers of tinfoil and fill with pie weights or 2 cups of uncooked rice.

Bake the crust for 30 minutes.

Remove the weights and foil.

Whisk together the eggs and yolks in a medium saucepan.

Whisk in the sugar, lemon zest, lemon juice, and salt.

Add the butter and cook over medium heat until the mixture thickens and the temperature reaches 170 degrees Fahrenheit.

Immediately pour the mixture through a fine mesh strainer into a separate bowl.

Stir in the heavy cream.

Pour the filling into the baked tart shell.

Bake the tart for 10 to 15 minutes, or until the center still has a little jiggle.

Cool the tart completely.

Remove the outer rim of the tart pan.

Decorate the tart with sweetened whipped cream, if desired.