Plum & cherry gâteau basque

Ingredients

• Nut pastry
• 400 gram flour
• 150 gram unsalted butter, softened
• 150 gram caster sugar
• 1 egg and 1 egg yolk – plus 1 beaten egg, for glazing pastry
• 1 teaspoon finely grated lemon zest
• Almond crème pâtissière filling
• 6 egg yolks
• 200 gram caster sugar
• 60 gram ground almonds
• 60 gram flour
• 1 litre litre full-fat milk
• 1 teaspoon vanilla paste
• To assemble
• 3 tablespoon good blackberry jam
• 1 cup cherries, stoned
• 10 ripe black doris plums, stoned (or use tinned plums)