Rhubarb and raspberry crostata

1.For pasta frolla, process flour, butter, icing sugar, vanilla seeds and a pinch of salt in a food processor until fine crumbs form. Add egg mixture, process until mixture just comes together, turn onto a lightly floured surface, knead lightly until smooth. Wrap in plastic wrap, refrigerate to rest (1-2 hours).

2.Meanwhile, place rhubarb in a colander, rinse under cold running water, then combine in a large saucepan with caster sugar, rinds, juices, ginger and vanilla seeds. Stir over medium-high heat until sugar dissolves, then bring to the boil and stir occasionally until very thick and jammy (10-15 minutes), add raspberries and set aside to cool completely.

3.Preheat oven to 180C. Roll out two-thirds of the pasta frolla on a lightly floured surface into a 3mm-thick rectangle and line a 13cm x 36cm rectangular tart tin, trim edges and spoon in cooled rhubarb mixture. Roll out remaining pasta frolla on a lightly floured surface to 3mm thick, then cut into 15mm-wide strips. Arrange strips in a lattice over jam, press pastry edges to seal and trim excess. Brush pastry with eggwash, dust with demerara sugar and bake until pastry is crisp and golden (40-45 minutes). Cool in tin before serving. Crostata is best eaten on day of making.