Dissolve the yeast with the milk and sugar in a bowl.

Let it rest for 5 minutes.

In another bowl, mix the flour with the butter cut into small cubes with your fingertips.

Then add the egg and mix with a spatula.

Add lastly the diluted yeast and finish working the dough with your hand for 5 minutes.

Form a ball and place it in the floured bowl.

Cover with a tea towel and leave to rest for 1 hour.

Work the butter with the sugar, vanilla and cinnamon, using a soft spatula or a spoon until you obtain a homogeneous pasty texture.

After letting the dough swell, roll it out with a rolling pin to form a large rectangle 2/3 mm thick.

Using a soft spatula, cover the dough completely with the filling.

Optional: you can add some raisins and/or crushed chocolate squares.

For this recipe, I left a part of dough with the "plain" filling, another with raisins on top of the filling, and another with chocolate chips on top of the filling, to make different types of rolls at once.

Roll the dough widthwise to form a single large roll. Cut the it into sections of about 3.5 cm.

Place the rolls in a large dish covered with baking paper. Brush the sides and top of the roll with the beaten egg yolk.

Cook for 13 to 15 minutes at 180°C.

Enjoy hot, warm or cold.