First of all, prepare the leavened dough, the brioche dough: place the flour in a bowl in a bowl and break the yeast over it.
Add sugar, lemon peel, chopped butter and egg.
Start kneading, then add milk and salt and knead until dough is elastic and well strung.
Cover the bowl with a clean cloth and let it rise at room temperature for at least 2 hours or until doubled.
Meanwhile prepare the custard: mix the egg yolks well with the sugar.
Add the flour and then the milk and the lemon peel.
Then cook over a low heat until a very thick cream is obtained.
Move it in a larger, cooler container, cover with plastic film and let it cool.
Take the dough again, deflate it with your hands, then divide it in half and spread it in two thin circles.
Place the first circle on a baking sheet covered with parchment paper, add the cream and the cherries, then close with the second circle, sealing the edges well and let rise again for 1 hour.
Brush the surface with the beaten egg yolk and sprinkle with the granulated sugar, then cook for about 25-30 minutes in a preheated static oven at 180 ° C.
The Polish aversana is ready, let it cool well before cutting it and serving it.