Instructions

1. Preheat the oven to 180C/350F/gas mark 4.
2. Grease and line a 23cm round deep spring-form tin with baking paper.
3. Put the egg yolks and sugar in a large bowl. Using an electrical whisk beat for a few minutes until pale and thick. Fold in the almonds and zest.
4. In a separate large bowl, whisk the egg whites with the extra spoon of sugar to soft peaks. Mix a little into the almond mixture to loosen, then fold in the rest until combined.
5. Pour into the cake tin and cover with flaked almonds.
6. Bake for 45 minutes, or until a skewer inserted into the centre of the cake comes out clean. If the almonds start to colour too quickly, cover loosely with foil.
7. Cool in tin and dust with icing sugar before serving.