Defrost the cherries in a sieve, collecting the juice. Finely chop the chocolate. Separate eggs. Whip egg whites and cream separately until stiff, chill.
Whisk vanilla pulp, egg yolks and 100 g sugar until white and frothy. Fold in cream and beaten egg white, finally fold in chocolate. Line a box or casserole dish (approx. 1.25 litres capacity) with baking or parchment paper. Pour in the mixture, smooth it down and freeze in the freezer for at least 5 hours
Remove the parfait from the freezer and let it stand at room temperature for about 15 minutes. Bring drained cherry juice and 5 tbsp. sugar to the boil. Mix the starch with a little water and thicken the simmering stock. Add the cherries, bring to the boil again briefly, remove from the heat, allow to cool slightly. Cut parfait into slices, arrange with cherries