If you do not have all the citrus fruits, you can replace one for another. No citrus fruit at all? Reduce some Orangina by half. For a more acidic flavour only boil half of the fruit juicesA tip from
1. Mix all the fruit juices together, place in a pan and bring to the boil to reduce the acidity; leave to cool down.
2. Cream together the butter, pinch of salt and the sugar, add the eggs one at the time and the egg yolk.
3. Sift together the baking powder and flour and gently add to the butter mixture.
4. Carry on whisking and slowly add the milk and the cold fruit juices.
5. Add the zests for extra flavour.
6. Pour into a 25cm cake tin greased with a little rapeseed oil and sprinkled with flour or icing sugar.
7. Leave to rest for 20 minutes before baking it in a pre-heated oven 180/200°C for approximately 40 minutes.
8. When cooked remove from the baking tin and leave to cool down.
9. To decorate make some caramel by placing 100g of sugar in a heavy base pan with a little water, bring to the boil and skim any froth. Leave to cook until golden without stirring it, pour in the lemon juice and leave to evaporate (a few seconds).
10. Dip the base of the pan in cold water to stop the cooking process and pour over a silicon mat and leave to set.
11. When set break into pieces, place in a food processor and ground to powder.
12. Sprinkle on top of the sponge and caramelise it with a blow torch.
13. Serve with low fat crème fraiche or natural yogurt.