Drain the plums in a sieve, collecting the juice. Halve large plum halves. Melt butter. Mix flour, sugar, salt and eggs. Stir in milk. Gradually stir in the butter.
Let the dough swell for about 15 minutes. Mix 50 ml prune juice and starch until smooth. Bring 400 ml plum juice to the boil. Add the starch while stirring and let it simmer for about 1 minute. Add the plums and let them cool down.
Grease the pan (approx. 24 cm Ø) in portions with a little oil. Put 1/8 of the dough into the pan. Bake one side until golden brown, turn the pancakes over and finish baking. Fry another 7 pancakes from the rest of the dough.
Keep pancakes warm. Mix sour cream, 2-3 tablespoons of milk and vanilla sugar. Arrange pancakes with compote and sour cream. Sprinkle sour cream with cinnamon and sugar. Dust with icing sugar.