Add the butter into the bowl of your stand mixer with the paddle attachment. Mix on medium speed for about 30 seconds until smooth and creamy.
Add in your sifted powdered sugar and salt and mix until combined and smooth.
Add in the vanilla and the egg and mix until combined.
Gradually add your flour while mixing on low until everything starts to come together and a dough forms.
Divide the dough into 2 pieces, wrap in plastic wrap and flatten into disks. Refrigerate for minimum of 1 hour before using your dough. If you skip this step, your crust will melt in the oven.
Leftover tart dough can be refrigerated for up to a week or frozen for 6 months.
To bake your tart, bring the dough out of the fridge or freezer for 30-60 minutes or until it's flexible enough to bend without cracking
Preheat your oven to 350ºF
Roll your tart dough out to ⅛" thick using a rolling pin and a flour dusted surface
Roll the dough up onto your rolling pin and unroll it into your tart pan
Carefully push the dough against the sides and corners of the tart pan
Then use your rolling pin to roll across the top of the dough to trim off the excess
Freeze your tart for 30 minutes
Place some tinfoil into the tart pan and fill it with some pie weights (or you can use dried beans or rice instead). Place the tart pan on a larger cookie sheet to easily lift and move it in the oven.
Bake your tart for 30 minutes, rotate the pan halfway through baking to promote even browning
Remove the foil and pie weights and bake for another 10 minutes to evenly brown the tart
Let the tart cool completely before filling it with things like pastry cream, lemon curd or ganache!