2. For the chocolate crust: (113gr) unsalted butter, at room temperature 1/2 cup (60gr) unsifted powdered sugar 3 egg pinch of salt 1 cup (160gr) white rice flour 1/4 cup (30gr) flour 1/4 (40gr) potato starch 1/4 cup (20gr) unsweetened cocoa powder For the chocolate truffle filling: 240gr bittersweet chocolate 12 tablespoons (170gr) unsalted butter, at room temperature 1/4 (50gr)cup sugar 1/4 cup (60ml) strong brewed coffee 4 large eggs For the chocolate ganache: 120gr bittersweet chocolate 1/3 cup heavy whipping cream 2 tablespoons unsalted butter, at room temperature
3. Prepare the crust: In a mixer, whip together the butter and sugar together until light and fluffy. Add the egg yolks and pinch of salt and mix until incorporated. Add the three different flours and cocoa powder and mix briefly. Dump the whole mixture onto a lightly floured (use more rice flour) board and gather the dough into a smooth ball. Do not work the dough while in the mixer or it will toughen it up. Flatten the dough into a disk, wrap it in plastic wrap and refrigerate for an hour. Preheat oven to 350F and position a rack in the center. Place eight tart rings on a parchment lined baking sheet and set aside. When the dough is nice and cold, roll it out on a lightly floured board or in between two sheets of plastic. Cut out eight 6-inch-rounds into the dough and fit them into eight 4-inch tart rings. If the dough tears while you roll or/and transfer into the rings, just patch it with your fingertips. Line the dough with pieces of parchment paper, fill with pie weights or dy beans and par bake for 10 minutes. Remove the weights and parchment paper. Keep the oven at 350F.
4. Prepare the filling: Place the chocolate in a medium bow and set aside. In a medium saucepan set over medium heat, bring the butter, sugar, and coffee together to a boil over medium. Pour the mixture over the chocolate and leave it undisturbed for 2-3 minutes. Gently whisk until smooth. Add the eggs, one at a time whisking quickly until the mixture is smooth. Divide the batter evenly among the tart shells and bake for 10 minutes. Let cool completely.
5. Prepare the chocolate ganache: Place the chocolate in a medium bowl and set aside. In a medium saucepan set over medium heat, bring the heavy cream to a gentle boil. Pour it over the chocolate and let sit for 2-3 minutes. Whisk until smooth and incorporate the butter at the same time until the ganache is completely smooth. Divide evenly on top of the tarts out with an offset spatula. Refrigerate until ready to eat.