In a food processor, add the flour, mahleb powder, if using, salt, and butter in a food processor and pulse to combine. Toss in the confectioners’ sugar and egg yolks and pulse until the mixture starts to come together into a dough.
Turn the dough out onto a lightly floured work surface and then gather it into a ball and gently flatten it to a disk, wrap it in plastic wrap, and refrigerate for an hour.
Butter a 9-inch (23-cm) fluted tart pan with a removable bottom. Grab a hand grater and use the coarse side to grate the pastry dough into the tart pan. Gently press the dough into the pan and up the sides, making sure that the bottom and sides are evenly covered and there are no gaps. [Editor’s Note: We know. This seems like a ridiculously unconventional way to make a crust. But trust us. It works. Trust us. Resist the urge to simply pat the dough into place.] Refrigerate for 30 minutes.
Meanwhile, preheat the oven to 400°F (200°C).
Line the pastry with a sheet of parchment paper and fill the crust with uncooked beans or rice to weight it and hold it in place. Then bake the pastry for 15 minutes.
Slowly and carefully remove the paper along with the beans or rice. Some of the pastry may separate; if this happens, gently press it back together with the back of a spoon. Bake the uncovered pastry until lightly golden, 7 to 15 minutes more. If the crust begins to brown at the edges, loosely cover the edges with a thin strip of aluminum foil.
Let the crust cool completely while you make the filling.