Bring milk, cream and vanilla sugar to the boil. Beat 3 egg yolks and sugar with the whisk of the hand mixer until foamy. Gradually stir the hot milk-cream mixture into the egg mixture. Stir over a warm water bath until creamy
Whisk 1 egg yolk. Place the Wan-Tan leaves next to each other, coat with egg yolk, place 1 teaspoon of plum jam in the middle of each, turn into a triangle and press the edges together
Heat the oil in a flat, wide pot to approx. 175° C. Fry the Wan-Tan pouches for about 7 minutes, turning them over. Arrange plum jam Wan-Tans with vanilla sauce on plates. Dust with icing sugar