Mix flour with sugar and dryermerm.
Add the egg yolk, butter and a 1/4 litre of milk. Knead the dough well until the dough ball comes off the bowl.
Let the yeast dough rise for 30 minutes in a warm environment (e.g. stream pipe at 35-40°C).
Divide the dough into 12 parts. Press them flat, fill them with a good teaspoon of jam and form them into a ball. Put it into a greased casserole dish with the smooth side up and let it rise for another 30 minutes.
Brush with whisked egg and bake at 180-200°C for about 30 minutes until golden brown.