Make the sable crust:

1. In a food processor, pulse together the flour, confectioners’ sugar, and salt, until combined.
2. Add in the cold cubed butter, then pulse until butter is mostly broken down into pebble sized pieces.
3. Add in the beaten egg, then pulse again until egg is fully distributed and the mixture looks like crumbly sand. Use your hands to gather the dough together and form into a disc. Wrap in plastic cling wrap, then place into the fridge to rest for 30 minutes.
4. After the 30 minute rest, unwrap and remove the dough from the fridge and place it onto a lightly floured work surface or overtop of a lightly floured parchment paper. Roll out into a 12-inch circle, and about 1/8 to 1/4-inch thick.
5. Transfer the dough into a 9-inch tart pan, press into the bottom and along the sides, then use a paring knife to cut off the excess dough.
6. Place into the freezer to firm up for 20-30 minutes.
7. Preheat the oven to 350F.
8. Remove from the freezer and use a fork to prick all around. Place parchment and pie weighs over top of the crust.
9. Bake for about 20 minutes. Remove from oven and remove the pie weights and parchment paper. Return to the oven and bake for an additional 10 minutes, or until lightly golden. When done, allow to fully cool before filling.

Make the lemon filling:

1. Turn the oven down to 325F.
2. Whisk together lemon zest, lemon juice, sugar, eggs, and egg yolks in a medium saucepan. Place over medium-low heat and heat while constantly whisking, until the filling has thickened to a hot pudding consistency (165F are read on a kitchen thermometer), about 8-10 minutes.
3. Immediately remove from heat and add in the cold cubed butter, heavy cream, and vanilla. Whisk until smooth and incorporated.

Assemble and bake:

1. Place a fine mesh sieve over the cooled crust, then pour the hot filling over the sieve. Press with a spatula to get most of the filling through.
2. Place the tart back into the oven to bake for 10-15 minutes, or until only the centre is a little jiggly.
3. Remove the tart from the oven and allow it to cool at room temperature for 30 minutes. Then, transfer to the fridge to fully cool for at least 8 hours, or preferably overnight.
4. Slice and serve as is, or feel free to decorate the top with whipped cream, lemon slices, and fresh berries.