1 To make the pastry, sieve the flour into a bowl. Add the diced butter and rub into the flour with your fingertips until the mixture resembles fine breadcrumbs. Sieve in the icing sugar and stir to combine. Lightly whisk the egg with the vanilla extract and pour two-thirds of it over the flour mixture (the remaining egg will be used to brush over the pastry). Use a dinner knife to mix in the egg before bringing the mixture together with your hands to form a dough. Wrap in clingfilm and refrigerate for 30 minutes to let the dough rest before rolling out.

2 On a lightly floured work surface, roll out pastry to a 20cm circle, 2mm thick (thin pastry is important as the pastry only has a short time to cook through).  Cut a piece of parchment paper just larger than the circle and transfer the pastry on to it.

3 When ready to bake, preheat oven to 190 degrees (fan). Place a baking sheet in the oven to heat up.

4 Gently heat the jam and stir in the cornflour, lemon juice and lemon zest.   Leaving a 3cm outer border, spread most of the jam over the pastry, then cover with the berries. Loosen the remaining warm jam with a little more lemon juice and lightly brush over the top of the fruit.

5 Fold the pastry border inwards over the fruit leaving the centre uncovered. Brush the exposed pastry with the remaining egg wash. Sprinkle with a little sugar.

6 Slide the filled pastry on to the hot baking sheet and bake in the oven for at least 30 minutes and until the crust is golden brown. Serve hot with freshly whipped cream (or a scoop of ice cream).