1. Sift the flour and cinnamon into a bowl or food processor, then put in the ground almonds, sugar, butter or margarine and grated lemon rind.
2. Process, without the plunger (to let in more air and make the mixture light), or rub the fat into the other ingredients with your fingers.
3. Either way, the result will be a soft dough. You can roll this out straight away, but it's easier to handle if you wrap it in polythene and chill it for 30 minutes.
4. Set the oven to 180 C/350 F/Gas Mark On a lightly floured board, roll out two-thirds of the almond mixture, to fit a 20 cm/8 inch flan tin.
5. Put the pastry into the tin and trim the edges.
6. Spread the jam over the pastry, then roll out the remaining pastry, including the trimmings, and cut long strips to make a lattice across the top of the jam.
7. Bake the torte for 30 minutes, or until the pastry is set and lightly browned.
8. Serve hot or cold, with a snowy topping of sifted icing sugar.