Make the pastry: rub the cold Unsalted Butter into the Plain Flour with a pinch of Salt until the mixture resembles fine breadcrumbs, then stir in enough cold Water to bring the dough together. Shape into a disc, wrap and chill for at least 30 minutes.
Roll out the chilled pastry on a lightly floured surface and line a tart tin, trimming any excess. Chill the lined tin while you preheat the oven to 180°C (350°F).
Blind-bake the case: line the pastry with baking paper, fill with baking beans or dried rice and bake until the edges are set and just beginning to colour. Remove the paper and weights and return to the oven for a few minutes to dry the base.
Spread a generous layer of Raspberry Jam over the warm tart shell and set aside to cool slightly.
Prepare the frangipane: beat softened Unsalted Butter with the Caster Sugar until light and fluffy, then beat in the Egg. Fold in the Ground Almonds, a spoonful of Plain Flour to help bind, and a few drops of Almond Extract for aroma.
Spoon the frangipane over the jam-lined shell, smoothing the top, then scatter the Flaked Almonds evenly across the surface.
Bake the tart at the same temperature until the frangipane is risen and golden and a skewer comes out clean from the centre. Allow the tart to cool in the tin.
Finish with a simple icing: mix the Icing Sugar with a little cold water to a thick but pourable consistency and drizzle or brush over the cooled tart. Leave to set, then remove from the tin, slice and serve.
