Makes approx. eight servings
Halve the plums and remove the stones. Scrape the seeds out of the vanilla pod, place them in a pan with the plums and the other compote ingredients, and simmer for approx. 20 minutes. Then leave to cool.
In the meantime, place the egg yolks, sugar and vanilla sugar in a bowl and beat with a hand mixer until pale and fluffy. Gradually add the mascarpone and the cream cheese. Mix in the lemon zest.
Line a flat-bottomed dish (approx. 25 x 18 cm) with half of the sponge fingers. Spread half of the plums on top. Spread half of the cream over the plums. Place the remaining sponge fingers on top of the cream. Layer the rest of the plums on top of the sponge fingers. Place the rest of the cream in a piping bag with a nozzle and decorate the top layer of plums with swirls of cream.
Refrigerate the tiramisu for around three hours. Sprinkle with cocoa powder before serving.