Preparation

Prepare leaven: in a bowl mix the yeast with a tablespoon of sugar, until dissolved. Add slightly warm milk and 1 tablespoon of flour, mix and set aside for 15 minutes.
Sieve the flour into a bowl. Add eggs and sugar to the mixer bowl, mix into a smooth mass. Add the leavening and the sour cream, mix. Add flour to wet ingredients. Install a dough hook and mix the ingredients until combined. Knead the dough adding butter piece by piece. After adding all the butter, knead for about 5 more minutes.

Place the dough in a greased bowl, cover and put it in the fridge preferably overnight or for at least 4 hours. Divide the dough into two parts, put one on a pastry board/mat and leave the other one in the fridge. Roll out a rectangle and fold it so that three layers are formed ( place one side in the centre and cover it with the other side). Roll it out again and fold again.

Divide the pastry prepared like this into two parts and roll each into a long rectangle of about 12-13 cm wide. Cut the rectangle into triangles. Put 1 teaspoon of Lauretta filling apple with cinnamon on the dough and form a croissant out of it. Place the croissants on a baking tray lined with baking paper and leave to rise for about 20 minutes.

Repeat with the second batch of dough. Mix the egg yolk with milk and use a brush to coat the top of the croissants. Sprinkle with sugar and cinnamon. Bake for about 20 minutes in 180 degrees until golden.