Pour the milk into a jug and add the yeast

Mix in well and leave to stand for 20 minutes

Pour the milk mix into the well and use your fingers to make a dough, mixing as quickly as possible

Cover with a cloth and leave to prove for an hour

Roll into a rectangle on a well floured surface

Dot a third of the butter on the pastry and then fold the top third down and the bottom third up

Roll out into a rectangle and repeat with a third of the butter

Fold as per above and roll out into a rectangle

Dot the rest of the butter on the pastry and fold as per above

Leave to rest for 30 minutes

Roll into a rectangle and cut into two or three lengthwise depending on how big you want your croissants

Cut squares and then cut each square into a triangle

Make a small cut into the base of each triangle, in the middle of the pastry

Place a block of chocolate on each side of the cut

Roll the pastry up from the base to the point

Place onto a lined baking tray and curve into a crescent shape

Preheat the oven to 220° Celsius

Leave the pastry to prove for 45 minutes

Brush with the egg yolk and bake for 10 minutes

Cool on a wire rack