1. Sift the flour, cocoa powder, and salt together. Set aside.
2. With a mixer, cream the butter for 1 minute until fluffy. Turn the mixer off, add the powdered sugar, and then mix on low until the powdered sugar has incorporated with the butter. Raise the speed to medium-high and cream the mixture for 1 minute.
3. Add the egg yolk, mix on medium until combined. Next, add the vanilla extract and mix.
4. Add the sifted dry ingredients to the bowl. Mix with a spatula until the dry ingredients are completely hydrated and the dough has formed. It will be soft and slightly sticky. Just make sure you see no streaks of dry flour in the dough.
5. Lay a piece of plastic wrap on the counter. Transfer the dough to the plastic, wrap it, and shape it into a disk.
6. Place the dough in the fridge for at least 2 hours. The dough can be made with up to 2 days in advance.

To assemble

1. Remove the dough from the fridge and let it sit on the counter for 5 minutes so it softens up slightly before you start rolling it out.
2. Sprinkle some flour on top of the counter, just don’t go overboard with it, because if you add too much flour to the dough, it might become dry and tough. To avoid using too much flour to roll out the dough, a good option is always to place the dough between two sheets of wax paper, and roll it out without using any flour at all.
3. Roll the dough until it’s about 3/4” thick.
4. At this point, carefully peel the dough off the counter and move it to a tart pan. You can use a 8, 9, or 10-inch pie/tart plate. If you use an 8, you might have a bit of leftover dough, which you can roll out and bake into cookies, since this dough is amazing!
5. If the dough breaks as you move it to the pie plate, don’t worry about it, because you can easily patch it up.
6. Use your hands to gently press the dough into the bottom of the pie plate and up the sides. Make sure the dough is about 3/8” thick, if it’s much thinner than that, you will end up with a crust that might break.
7. Use a knife to run along the edges of the pie plate to trim the excess overhanging dough.
8. Place the pie plate in the fridge for 30 minutes, or in the freezer for 15 minutes before baking.
9. Meanwhile, pre-heat the oven to 350ºF.
10. Remove the dough from the fridge, and poke the bottom with a fork, to release air as it bakes and so that big air bubbles won’t form in the bottom of the crust.
11. Bake in the pre-heated oven for 20-30 minutes. Once the dough has a deep color, and doesn’t seem wet anymore.
12. Remove and let it cool completely before removing from the tart pan, or before filling it.

Storage

1. This dough can be frozen for up to 2 months. To freeze, you can wrap the dough tightly in plastic wrap and place it inside of a freezer zip loc bag. Or you can freeze the dough already assembled in the pie plate, if it’s a metal pie plate, I avoid freezing glass.
2. The baked crust will last for up to 3 days in an air-tight container, at room temperature.