Slice the 120g of cold better into 4 pieces.
Place the slices over baking paper.
Fold the baking paper over the butter to form a square pocket to about 20 x 20 cm.
With a rolling pin, stretch the butter to fill out the pocket.
We want a thin square layer of butter.
Refrigerate for a few minutes so it hold its shape.
Roll out the dough to about double the size of the sheet of butter.
Place the cold sheet of butter in the centre and fold the dough over to the centre.
Roll it out to about double the size length wise.
Then fold 3/4 to the centre and repeat with the other size.
Fold in again in half to form a log.
Cover again with plastic wrap and refrigerate for 20 minutes.
Roll it out again into a square shape.
Fold it again sides to centre then in half.
Cover and refrigerate again for another 20 minutes.
Roll it out again into a 20cm square shape.
Slice the dough into 4 equal strips.
Get one of the strips shape into a side ways C shape, get the next strip shape the same way and place each C facing each other and then press both together.
Place in a baking tray lined with baking paper.
Repeat with the last 2 strips.
Cover and let it rise in a warm place for 2 hours.
Brush with a egg yolk.
Bake in pre heated oven 170C | 338F for 20 minutes.
After 20 minutes raise the temperature to 200C | 392F and bake for another 5 minutes or until golden.
Once baked brush it with butter to give a nice shine to it.