Step 1

For pastry, place flour, sugar and a pinch of salt in a food processor. Add butter and process to form fine crumbs. Add egg and yolk, then pulse until the mixture comes together in a smooth ball. Enclose in plastic wrap and chill for 30 minutes.

Step 2

Preheat oven to 180°C. Grease a 36cm x 11cm rectangular loose-bottomed tart pan. Pulse nuts in a processor to coarse crumbs. Add eggs, sugar and vanilla, then pulse to combine – don't over-mix.

Step 3

Remove dough from fridge and set one-third aside. Roll out the remaining dough to a 5mm-thick 40cm x 15cm rectangle and use to line the pan. Fill with walnut mixture. Roll out reserved dough to a 5mm-thick rectangle. Brush edges of tart with water, then top with extra pastry, pressing edges to seal. Trim excess, then brush top with egg and milk mix. Bake for 30-35 minutes until golden.

Step 4

Meanwhile for the prunes, place sugar, vanilla pod and seeds and 1 cup (250ml) water in a pan over low heat. Stir to dissolve sugar. Turn heat to medium and simmer for 5-6 minutes until reduced. Add prunes and soaking liquid, then cook over low heat for 3-4 minutes until syrupy. Set aside until needed.

Step 5

Cool the tart in the pan on a rack for 10 minutes, then remove from pan and dust with icing sugar. Slice the tart and serve warm with some of the prunes and a dollop of creme fraiche.