The next day, split your dough in two. One part should be bigger — it will line the base of the dish and come slightly up the sides. The top one is simply laid over the filling.
On a floured surface, roll the dough out fairly thinly, because the baking powder will make the cake rise and could leave it dry if you keep it too thick (especially as, if you’ve followed my proportions, we haven’t used much butter).
Lay it in a buttered tin, letting it overhang. You can use a tart tin or a sponge tin.
Roll out the second piece on the work surface, flouring it again. Before laying the second piece on, fill the tart with the cherry jam.
Bake for 40 minutes at 160 °C.