Preparation

Make the preserves

• Put the figs, sugar, vanilla seeds and pod, and lemon zest and juice in a medium heavy-duty saucepan, and stir to combine. Cook over low heat to dissolve the sugar, about 10 minutes. Use a potato masher to break up the figs a bit. Raise the heat to medium high, and bring to a boil. Reduce the heat and simmer, stirring often, until the mixture has thickened, about 10 minutes. Stir in the Cognac and cinnamon, and cook until thickened to a jam consistency, 2 to 3 minutes more. You should be able to drag a path through the bottom of the saucepan with a silicone spatula or wooden spoon. Remove from the heat, add the chocolate, and stir until melted and thoroughly combined. Discard the zest and vanilla pod. Scrape the jam into a heatproof bowl and let cool completely. (The preserves can be stored in an airtight container in the refrigerator for up to 2 weeks.)

Assemble and bake the tart

• Position a rack in the center of the oven, put a large rimmed baking sheet on the rack, and heat the oven to 350°F. Remove the pasta frolla from the refrigerator and let it rest at room temperature for 30 minutes. Have ready a 9-inch fluted tart pan with a removable bottom.
• Lightly dust a work surface and rolling pin with flour. Roll the larger disk of pasta frolla into a 12-inch circle, lifting and turning the dough as you roll to prevent sticking and create an even round. Gently wrap the dough around the rolling pin and unroll it over the tart pan. Gently fit the dough into the pan without stretching it. Use the palm of your hand or the rolling pin to trim off the excess. Refrigerate while you roll out the second piece of dough.
• Roll the smaller piece into a 10-inch circle, and use a fluted pastry wheel to cut it into strips from 1/2 inch to 1 inch wide. (For a more traditional look, divide the disk into 10 pieces, and with your hands, roll each piece into a 10-inch rope.)
• Remove the crostata base from the refrigerator and spoon the jam into it, spreading it evenly. Position the strips of pastry on top of the jam in a crisscross lattice pattern. You can weave the strips if you like, but the dough is fragile and tends to tear so it’s not necessary (nor is it traditional). Press the edges of the strips into the edge of the tart shell to secure, and trim off the excess.
• Put the crostata on the heated baking sheet and bake until the crust is set and smells like toasty chocolate (it’s difficult to tell if a chocolate crust has browned), 30 to 35 minutes. Transfer from the baking sheet to a rack to cool completely. Remove the ring, use a large, wide-angled spatula to transfer the crostata from the metal tart base to a serving plate. Dust with confectioners’ sugar, if using, and serve.