Roll out the pastry on a lightly floured board to 5mm thick.
Grease and then line an 20cm deep tart tin with the pastry. Prick the base all over with a fork. Chill in the refrigerator for 20 minutes.
Line the tart case with baking/greaseproof paper and fill with baking beans. Cook for 15 minutes or until the pastry is a pale golden colour. Remove the baking beans, cook for a further 5 minutes.
Spread the raspberry jam onto the base of the pastry case, leave to one side.
Cream the butter and sugar together until pale in colour with an electric beater. Beat the egg yolk into the beaten eggs and slowly add to the creamed butter and sugar a little at a time. Gently fold in the ground almonds, lemon zest and almond extract.
Pour the mixture in to the pastry case and gently level the surface to ensure the whole case is filled. Bake for 30 minutes, remove from the oven, sprinkle on the flaked almonds and return to the oven for a further 10 minutes or until golden and set. Sprinkle with icing sugar whilst still warm.
The filling of this tart contains no flour instead uses ground almonds.