Process the pistachios into fine crumbs, then add the flour and icing sugar, mixing until just combined.

Add the chilled butter and pulse until the mixture resembles breadcrumbs.

Gradually pour in the iced water until the dough comes together. Shape into a disc, wrap tightly, and chill in the fridge for 30 minutes.

Lightly grease a 23cm round tart pan with a removable base. Roll out the dough on a floured surface to about 4mm thick and line the pan, trimming the edges.

Refrigerate the lined pan for another 30 minutes.

Preheat the oven to 180°C (350°F).

Blind bake the pastry case for 20 minutes, then uncover and bake for another 15 minutes until golden and crisp.

Let it cool completely.

In a saucepan, combine the milk and vanilla bean paste, heating it to a near-boiling point.

In a large bowl, whisk the egg yolks and caster sugar until pale and thick.

Whisk in the cornflour and plain flour, then gradually stir in the warm milk mixture until smooth.

Return the mixture to the saucepan and cook over medium heat, stirring constantly until the custard boils and thickens.

Pour the custard into the cooled pastry case and smooth the surface. Chill for at least 2 hours until cold and firm.

Blend the raspberries, caster sugar, and water until smooth, then strain through a fine sieve.

Sprinkle the gelatine over 2 tablespoons of just boiled water, whisk to dissolve, and mix with the raspberry mixture and rosewater.

Pour over the chilled custard and return to the fridge for another 2 hours or until set.

Decorate the tart with chopped pistachios and rose petals before serving.