Use this crust to make any number of chocolatey treats.
Place the flour, cocoa, sugar, and salt in the bowl of a food processor, and pulse several times to combine. Add the butter, and pulse until the mixture resembles coarse meal, about 10 seconds. Add the egg yolks and vanilla, and process just until mixture begins to hold together, no more than 30 seconds.
Turn dough out onto a lightly floured surface, and form into a disk. Cover in plastic wrap; refrigerate for 30 minutes, or until ready to use.