Peel the apples, then grate and drizzle with lemon juice so they don't brown.
Melt the butter in a bowl. Reserve.
Separately, combine the sugar with the cinnamon.
In another bowl, beat the egg. Reserve.
Brush the dough with the melted butter and distribute the apple, sugar and cinnamon.
Take both ends of the dough and start rolling. At the end, pinch and seal the sides, like an envelope, so it doesn't leak. Brush with the beaten egg. Grease a mold with butter and bake in a preheated oven at 180°C for about 40 minutes. When serving, sprinkle icing sugar over the dessert with a sieve.