For the pastry, pulse the flour, icing sugar and butter in a food processor until the mixture resembles fine breadcrumbs. Add the vanilla seeds and pulse briefly. Remove from the food processor and pour the crumbs into a large bowl. Add the eggs and use a blunt knife to form a paste. Roll into a ball, flatten, cover in cling film and chill in the fridge for 30 minutes.
For the gooseberry and elderflower jam, place a saucer in the freezer.
Smear the bottom of a large saucepan with the butter, then add the gooseberries and water and simmer for 15 minutes or until the gooseberries are tender. Reduce the heat, add the sugar and stir until well combined. Let this mixture heat through until the sugar has dissolved then increase the heat and boil for 8-10 minutes. Remove the pan from the heat and drop a teaspoon of the mixture onto the chilled saucer - you are looking for a skin to form on the surface once it has cooled. If it hasn’t, continue to boil, checking every five minutes, until the setting point is reached. Put the jam into a bowl and allow the mixture to cool a little before stirring in the cordial.
Preheat the oven to 180C/350F/Gas 4. Grease two 12-hole petit four tins.
Roll the pastry out thinly on a floured work surface and use it to line the petit four tins. Chill in the fridge for 30 minutes.
Meanwhile, for the frangipane, beat the eggs in a jug and set aside. Beat the butter and sugar until light and fluffy then add the beaten eggs a little at a time until well combined. Stir in the ground almonds.
Spoon a little jam into the bottom of the tart cases, cover with a little frangipane then bake in the oven for 15 minutes or until the filling is just beginning to set. Arrange the flaked almonds in a flower pattern on top of the tarts then return them to the oven for 10-15 minutes or until golden-brown. Cool on a wire rack.