Preheat oven to 150 degrees C. Line two baking trays with baking paper.

Using electric beaters whisk the egg whites with the lemon juice in a clean bowl until thick and foamy, then begin to add sugar and ground hazelnuts, beating all the while. Beat until egg whites form stiff peaks. Whisk in the grated marzipan.

Spoon the macaroon batter into a pastry bag fitted with a star tip and pipe out the macaroons, about 4 cm in diameter, onto the baking trays.

Bake for 12-15 minutes or until the macaroons are golden. Allow to cool completely on a wire rack. Store in airtight container