For the pastry, beat the icing sugar, cinnamon and 90g of the butter in an electric mixer for 2-3 minutes. Add 2 of the eggs, one at a time and beat well to combine.
Sift in 300g of the flour, and gently fold in the ground almonds and a pinch of sea salt. Turn onto a lightly floured work surface and knead lightly until smooth. Wrap the pastry in cling film and refrigerate for at least 30 minutes.
Roll out a third of the pastry on a lightly floured work surface to 2mm thick and cut into long strips. Transfer to a baking tray and return to the fridge for later.
Roll out the remaining pastry to line a 28cm x 20cm baking tin and place tin on an oven tray. Refrigerate for 20 minutes while you make the filling.
Preheat the oven to 160ºC, fan 140ºC, gas mark 3.
Place the cherries, plums and currants in a saucepan with 200ml of water, and stir over a medium heat until all the liquid is absorbed. Let cool slightly.
Melt the remaining 50g of butter in a saucepan over medium heat then cool.
Whisk the remaining egg, brown sugar, seeds from the vanilla pod (scraped out with the tip of a knife) and nutmeg and ground spices until thick and pale. Fold in the melted butter and remaining 50g of flour.
Fold in the fruit mix and spoon into pastry-lined tin. Decorate the top with the reserved pastry strips in a lattice pattern.
Bake for 18-20 minutes in the preheated oven until firm.