Mix 50 ml milk, 20 g sugar and pudding powder. Boil 150 ml milk. Stir in the pudding powder and let it simmer for about 1 minute while stirring. Pour the pudding into a larger bowl, cover the surface with foil. Let the pudding cool down, chill after about 15 minutes.
Pour the cherries into a sieve, let them drip off and collect the juice. Mix 2 tablespoons of juice and starch. Bring 75 ml juice and 1 teaspoon sugar to the boil. Stir in the starch and let it simmer for about 1 minute while stirring, let it cool down for about 15 minutes, then add the cherries.
Chop Cantuccini very finely. Stir the pudding with the whisks of the slope mixer until smooth. Whip the cream until stiff and fold into the pudding. Arrange pudding and cherries in bowls. Sprinkle the cantuccini over the pudding and serve immediately.