Drain the cherries, collecting the juice. Remove about 4 tablespoon of the juice and use it to mix the pudding powder with the sugar. In the meantime, bring the juice in the saucepan to a boil. Then stir in the mixed pudding powder, immediately add the cherries and let everything boil briefly. Then let it cool down a bit.
Cut the puff pastry into beautiful medium-sized slices, put about 2 tablespoons of the cherry pudding in the middle of each slice, fold the puff pastry over and press lightly. Cut a kind of comb into the pressed side. Whisk the egg yolk with a little water and brush the puff pastry pieces with it.
Bake in the oven at 200 ° C for 15-20 minutes.
Make a glaze from powdered sugar, a little lemon juice and a little water and brush the combs with it.