In a small saucepan heat the sugar, zest and juice of 2 of the lemons and 50ml water. Cook over a low heat until the sugar is melted then bring up to a boil and reduce for 2-3min until thickened, stir in the limoncello. Leave to one side to cool.
In a large bowl beat the mascarpone until smooth. Lightly beat in the cream until just thickened, fold into the mascarpone with the icing sugar, and swirl in the lemon curd like a ripple effect.
One by one, lightly soak half of the sponge fingers in the syrup and lay across a 20x30cm ceramic dish. Spoon over half of the lemon ripple cream, and half the summer berries. Repeat with the remaining sponge fingers and cream. Top with the remaining summer berries. Leave to set in the fridge for at least 3hours.
Shred the reserved lemon zest into fine julienne strips. In a heavy based saucepan add the second weight of sugar and 200ml water. Simmer over a low heat until all the sugar has dissolved then turn the heat up and add the lemon zest. Simmer gently for 10 minutes until translucent. Remove from the heat, pour into a bowl to cool. Decorate the top of your tiramisu with the lemon zest and some of the syrup spooned over the fruit. Keep remaining syrup for the base of a Prosecco- cheers!
Soaking Syrup
100g caster sugar
Zest peeled from 3 lemons, then juiced
100 ml limoncello
For the layers
500g mascarpone
600 ml double cream
3 tbsp icing sugar
100g lemon curd
200g savioardi sponge fingers
300g mixed summer berries
To decorate(optional)
2 large lemons
200g caster sugar