Ingredients

Step by step

1. Line the base of a 20cm square, loose-bottomed cake tin with baking paper.
2. Put the pistachios and biscuits in a food processor and blend to fine crumbs. Add the melted butter and whiz again for 5 seconds, then tip the mixture into the tin and press down evenly and firmly (use the end of a rolling pin to compact the mixture). Chill in the fridge for at least 20 minutes.
3. Put 6 tablespoons Prosecco in a small pan and add the gelatine leaves. Leave to soak for 10 minutes until softened.
4. Meanwhile, put the condensed milk, cream and cream cheese in a large bowl and whisk with an electric whisk for 5 minutes until smooth and thickened.
5. Warm the Prosecco mixture over a very gentle heat, stirring all the time until the gelatine just melts and the liquid is clear. Do this very carefully, ensuring that the mixture is just warm – if too hot, it will set when added to the cheesecake mixture so it should be no more than lukewarm.
6. Whisk the Prosecco and gelatine mixture into the cream then pour on top of the biscuit base. Tap the tin gently so that the surface of the mixture is level, then leave to chill in the fridge for 3-4 hours until set.
7. Meanwhile, quarter the plums, discarding the stones. Put them in a bowl and cover with clingfilm. Pierce a hole in the clingfilm, then cook in the microwave on high power (800-900 watts) for 5-6 minutes until tender. Or cook gently in a pan with just 1 tablespoon water, covered, until soft. Press the plums through a sieve and leave the juice to cool, discarding the skins and pulp from the sieve.
8. Put 4 tablespoons Prosecco in a small pan, add the gelatine and leave to soften for 10 minutes, then heat as before. Gradually stir in the plum juice then pour it over the set cheesecake. Chill in the fridge for at least 1 hour until set.
9. To decorate, whisk the egg white with a fork until frothy. Put the sugar in a separate bowl. Dip little bunches of redcurrants into the egg white, shaking off the excess, then dip in caster sugar. Leave to dry on a tray lined with baking paper for at least 4 hours.
10. When ready to serve, remove the cheesecake from the tin, peel off the baking paper and cut it into 25 squares (about 4cm). Arrange the redcurrants on top of the squares.