First, take out the butter for the creases and let it soften a little.
In the meantime, put flour, sugar, butter and brewer’s yeast in the mixer bowl and start kneading, then add water and salt.

Place the butter from the folds on a large sheet of baking paper, fold the paper over it and roll it out with a rolling pin until you obtain a rectangle, then place it back in the refrigerator.

Meanwhile, continue kneading until you obtain a homogeneous dough, wrap it in cling film giving it a rectangular shape and leave to rest in the fridge for at least 2 hours (even better overnight).

Roll out the dough on a lightly floured work surface until you obtain a rectangle 7-8 mm thick, with the short side about as wide as the sheet of butter and the long side about twice as wide.
Place the sheet of butter in the center of the dough and fold the upper and lower edges over it until they join together.

Turn the dough so that the cut is vertical and roll it out with a rolling pin to make it stretch until you obtain a sheet of 6-7 mm thick.
Fold the bottom third to cover the third in the middle, then cover both with the top flap.
Wrap with cling film and place in the fridge for 1 hour, then repeat: roll out vertically until you obtain a 6-7 mm sheet and fold the lower and upper edges over the middle third again.

Wrap it in the same film and put it back in the fridge for another hour, then take the dough and lightly flour it.

Roll out the dough until you obtain a sheet of approximately 26×40 cm, then roll it up on itself starting from the short side, wrap in cling film and place in the fridge for 1 hour.

Take the roll and cut it into slices about 2 cm thick.

Place on a baking tray lined with baking paper, possibly inside small 8cm pastry cutters or molds (so that they grow very high and not too wide).
Cover with another sheet of baking paper, place a baking tray on top and leave to rise in the switched off oven for at least 2 hours or until doubled in size.

Take the croissants out of the oven and preheat it to 200°C in fan mode.
Beat the egg yolk with the cream and brush them, then put the baking paper and baking tray back on top and cook for 8 minutes, then lower the temperature to 180°C and cook for another 12-13 minutes.
Finally, remove the baking tray and baking paper and cook for another 5 minutes or until golden brown.
Leave to cool on a wire rack before removing the pastry cutters.

Once completely cold, fill with Nutella using a piping bag with a long, thin nozzle.

Melt the chocolate pieces in the microwave or in a bain-marie and decorate one side of each croissant, then sprinkling with pistachios.

The croissant rolls are ready, all you have to do is let the chocolate dry before enjoying them.