Mix 2 teaspoons of hot chocolate powder with 50ml of warm boiled water until smooth.
Layer half of the sponge fingers in a trifle bowl and drizzle with half of the chocolate mixture.
Place eight mandarin segments on top of the soaked sponge fingers.
Whisk the cream cheese in a bowl until smooth.
Whisk the yoghurt and vanilla extract into the cream cheese until well combined.
Spoon half of the cheese mixture over the fruit and smooth with a palette knife.
Repeat the layers of sponge, chocolate, mandarins, and cream, then dust with chocolate powder.
Cover with film and chill in the fridge for one hour.
Serve with extra mandarin segments as a garnish.