Combine all the ingredients and knead for about ten minutes until you have a nice ball. Place the dough in a bowl, seal tightly with plastic wrap, and let it rise for at least 1 hour in a warm place.
An hour later
Peel the apples. Remove the bottom half of the core with an apple corer. Cut the core halfway loose by going horizontally through the apple with the tip of a knife. The top centimeter of the core and the stem should remain intact!
Mix the brown sugar, butter, and cinnamon into a thick paste and fill the holes of the apple cores with it. Press down well.
Preheat the oven to 190 °C.
Take the dough out, sprinkle some flour on the work surface, and divide the dough into four pieces (or five, depending on the number of apples).
Roll each piece out into a round sheet.
Place the apple on it and try to estimate how much dough you need to completely wrap it.
Cut the dough to size, by hand or with a circle cutter.
Poke a hole in the middle and place it over the stem. Fold the dough nicely closed at the bottom.
Beat the egg yolk with the milk and brush each apple with the mixture for a shiny crust.
Place the apples in a fireproof dish and bake them for 20 to 25 minutes, depending on the size of the apples.
Tips
The yeast dough has to rise for an hour!