Step 1

In the bowl of your stand mixer fitted with the paddle attachment, thoroughly mix together the flour, sugar, cocoa powder, espresso powder (if using) and salt.

Step 2

Add the softened butter and mix on low to medium-low speed until the butter is completely incorporated.

Step 3

Add the egg yolk and vanilla extract and mix well.

Step 4

Add the cream and mix for 15-20 seconds. The dough should come together in a big lump stuck to the beater. If this doesn't happen, add more cream, a tiny bit at a time, until the dough comes together. There shouldn't be any dry ingredients fluttering about, nor should the dough be sticky. It should be about the consistency of Play-Doh.

Step 5

Remove the dough from the mixer and form it into a disc about 1" thick.

Step 6

Place the disk between two sheets of parchment and roll to about 3/8" thick.

Step 7

You can line a tart pan immediately or, if you're making cookies, refrigerate the sheeted dough until it is firm.

Step 8

Place the dough over a 9" tart pan (8" or 10" is fine too, depending on what sort of tart you'll be making. You can even line a regular pie pan with the dough). Leave at least 1/2" overhang all around.

Step 9

Working slowly around the tart pan, lift an edge of the dough and then press the dough into the corner of the pan. Don't stretch the dough or it could shrink back on you. Use the back of your knuckle to press the dough into the corners. Especially if you have long nails, don't use your fingertips or you could poke holes in your dough.

Step 10

Trim the the dough to have a more-or less even overhang. I used kitchen scissors.

Step 11

Fold the excess dough over inside the tart pan and press it against the dough already lining the sides. This will give you a double thickness on the sides and will help make your tart nice and sturdy.

Step 12

Using a small spatula or knife (I used a small offset icing spatula), trim the dough even with the edge of the tart pan. Sweep the knife/spatula from the inside to the outside across any dough sticking out over the top of the pan. The edge of the pan will sort of act like a cutter, giving you a nice even edge.

Step 13

Save the scraps and re-roll once. You can use the extra for cookies.

Step 14

Refrigerate the tart shell on a cookie sheet (because of the removable bottom) until firm.

Step 15

Poke tiny holes all in the bottom of the tart shell with a small, sharp knife. (I find a fork makes holes that are too big. You don't want your filling to leak out.)

Step 16

Refrigerate or freeze for about 30 minutes.

Step 17

Line the bottom of the tart pan with parchment (crumble it up and then uncrumble it to make it easier to fit it in the corners) or a commercial-sized coffee filter and add some beans or pie weights.

Step 18

Bake at 350F (still on the cookie sheet) for about 20 minutes.

Step 19

Remove from the oven and carefully lift up the parchment or coffee filter. This dough is delicate, so if it's too wet, it might stick to the parchment. Worry not. Just put it back in the oven for another 5 minutes or so and check it again.

Step 20

When the dough in the bottom of the pan is set up enough that it doesn't stick, carefully remove the paper and beans. Put the tart shell back in the oven for another 10-15 minutes, or until the bottom is completely dry. The crust will firm up as it cools. If it seems a bit soft, you can absolutely stick it back in the oven for another few minutes, and nothing bad will happen.

Step 21

Let the tart shell cool completely on a rack.