There are many make-ahead opportunities for preparing this dessert, so you can have it on hand whenever you want. The hazelnut dough can be made and frozen for up to 3 months. Form it into a disk and wrap it in plastic wrap for added protection against freezer burn, and slip the wrapped dough into a ziplock plastic freezer bag. Thaw the dough, still wrapped, in the refrigerator. You can also form and bake the tart shells a day ahead, and store them at room temperature; or you can cool them completely, wrap in aluminum foil, transfer to a ziplcok plastic freezer bag, and freeze for up to 1 month. The filling comes together in minutes, but you can mix it 2 days ahead and store it in the fridge until you’re ready to assemble the tarts. Bring the filling back to room temperature before spooning it into the tart shells.