1. Put the lemon in a saucepan cover with water and bring to the boil. Reduce the heat and simmer for 1 hour.
2. Halve the lemon remove the pips then puree in a blender skin and all.
3. Preheat the oven to 170C. Oil a 20cm round spring form cake tin and line with a disc of baking parchment.4 Beat the eggs and sugar together until pale and thick. Fold in the flour baking powder almonds and lemon puree.
4. Pour the mixture into the tin and bake for one hour until the top is golden.
5. Keep an eye on the cake for the last 15 mins as the fructose sugar is slightly more likely to catch. The cake will be quite dark though.
6. Leave to cool for 10 minutes then turn out on to a rack and cool completely.