Pulse flour, sugar, butter, almonds, baking powder, and zests in a food processor into breadcrumbs.
Pulse in the beaten egg until a dough forms and chill for 30 minutes.
Preheat the oven to 200°C and grease two six-hole petit four tins.
Boil milk and vanilla seeds in a saucepan while whisking.
Beat sugar and egg yolks until thick then whisk in cornflour paste.
Whisk hot milk into the egg mixture, return to heat, boil, then stir in elderflower cordial and chill.
Line tins with rolled pastry and bake for 7-10 minutes until golden.
Boil sugar and half the apple juice in a saucepan.
Thicken juice with cornflour and syrup by boiling then set aside to cool.
Fill pastry cases with cream, top with fruit, drizzle with glaze, and chill.