Plum Tart

First, prepare the plum jam by following the instructions on the Ar.pa Prestomarmellata sachet. Leave it to cool completely before using the amount needed to fill the tart. Any remaining jam can be stored for later use.
Meanwhile, prepare the shortcrust pastry. Place the flour in a large bowl and add the cold butter, cut into small cubes. Rub the butter into the flour using your fingertips until the mixture resembles fine breadcrumbs.
Add the caster sugar, Ar.pa Vanilla Baking Powder, the pinch of salt and the grated lemon zest. Stir in the whole egg and the egg yolk, then mix until a smooth, even dough forms.
Wrap the dough in cling film and chill in the refrigerator for approximately 30 minutes.
After chilling, set aside a small portion of the pastry for the lattice topping. Roll out the remaining pastry on a lightly floured surface to a thickness of approximately 4–5 mm.
Line a 24 cm tart tin with the pastry, prick the base with a fork and spread the plum jam evenly over the surface.
Roll out the reserved pastry and cut it into strips. Arrange them over the filling to create the traditional lattice pattern.
Bake in a preheated conventional oven at 175 °C for 35–40 minutes, or until the pastry is lightly golden.
Allow the tart to cool completely before removing it from the tin. If desired, finish with a light dusting of icing sugar before serving.