Follow the directions in the blueberry curd recipe. Once the curd is done either bake it right away with the chocolate cinnamon crust or refrigerate it until you're ready to make the tart.
Make the Chocolate Tart Crust
The crust can be made up to 1 day in advance. If made in advance, let the tart crust completely cool and then cover with plastic wrap.
Preheat the oven to 350°F.
Whisk flour, cocoa, sugar, and salt together in a bowl. Add the melted butter and stir with a silicone spatula or wooden spoon until a dough forms and no specks of flour remain. Using your hands, press two-thirds of dough into the tart pan with removable bottom. Press remaining dough into fluted sides of the pan. Press and smooth dough with your hands to even thickness. Dock the bottom of the tart dough with the times of the fork before baking.
Place pan on a wire rack set in a rimmed baking sheet and bake on the middle rack, until firm to touch, 25 minutes, rotating pan halfway through baking. The dough will bubble as it is cooking. If you see the edge of the tart crust start to crack at the edge of the tart pan, you baked it too long.
Remove the crust from the oven and set it aside until ready to fill with the blueberry curd.
The crust can be made one day in advance. If making it in advance, allow it to cool to room temperature and cover with plastic wrap.
Assemble and Bake the Tart
If making the blueberry curd, tart crust and tart all in the same day, bake the tart crust and while the tart crust is baking make the blueberry curd.
Pour the curd into the tart crust and bake the curd for 15 minutes.
The curd will still be jiggling, but it should be darker.
Remove the tart from the oven. Let it cool to room temperature. Refrigerate the tart until ready to serve. Right before serving decorate it with fresh fruit, whipped cream or meringue.
Storage
The tart will be good in the refrigerator for up to 5 days, but after 2 days the crust will be soft. It will still taste good, but the crust won't be as crisp as it originally was.