Place in food processor and blitz with the lemon juice. Stir in the polenta, baking powder and vanilla sugar and then the ground almonds. In another bowl, beat the eggs with the sugar into a fine white foam.
Carefully fold the polenta mixture into the airy egg foam and pour into a thoroughly greased 26-cm (10-inch) cake tin.
Peel the oranges for the garnish. Using a sharp knife, trim the top and bottom of an orange including the pith. Place the orange in front of you on the cutting board and cut the peel from top to bottom removing all of the pith, leaving only the pulp. Cut the orange into slices. Continue until all oranges are cut.
Cover the top of your cake with overlapping orange slices.
In the meantime soak the gelatine sheets in cold water. Or dissolve the powdered gelatine in a small amount of warm water. Heat the jam in a saucepan and press through a sieve. Squeeze the water out of the gelatine leaves and stir them into the hot jam until dissolved. Or add the dissolved powdered gelatine. Spread the oranges on the cake with the jam and allow to set.
© 2011 All rights reserved. Published by Murdoch Books.