Place the pineapple in a sieve to drain. Fill the pineapple juice up to 380 ml with water. Mix the starch with sugar and vanilla sugar and stir with 6 tablespoons of the juice mixture. Bring the remaining juice to a boil. Remove from the heat. Stir in the starch mixture and bring to a boil briefly. Chill. Stir occasionally. Stir the lemon juice into the lukewarm mixture.
Stir the chopped pineapple pieces into the cream.
Finally, whip the cream until stiff and fold into the cream.
Allow to set in the refrigerator.