The glass we use here is about 200 ml, in case you were wondering :)
In a large bowl, sift together flour and baking powder then, using a fork, make a well in the center and add all the other ingredients, blending everything with a spoon to form a soft dough. Gather the dough into a ball, wrap the ball in cling film and refrigerate until firm, at least 30 mins.
Preheat the oven to 350° and line a crostata dish with parchment paper.
Using a knife, cut two-thirds of the dough from the ball and roll out the dough inside the crostata dish, gently pressing it down with your fingers to create an even base layer. Spoon the jam into the tart shell and spread it evenly.
Now, when the shell is ready and the jam is nicely spread, roll out the remaining dough between sheets of wax paper and cut some cute, decorative strips, then arrange the strips across the tart to form a lattice.
Bake the tart in the hot oven for 25 minutes, or until the crust is golden and crisp.
You can keep your crostata for a couple of days in it's own dish, covered in aluminium foil, or cut into squares and stored into a tin box.