In a large bowl combine the eggs, yeast, salt, and sugar. Whisk until the sugar has dissolved.
Add 4 tablespoons of the flour and whisk until smooth to incorporate the softened butter.
Add the butter and whisk until smooth.
Add the remaining flour and mix to form a dough.
Rest the dough for 20 minutes.
Perform 4 folds refrigerating the dough for 20 minutes after each fold.
Cold ferment the dough for 12 - 24 hours.
Divide the dough into 3 equal pieces, pre-shape, and let it rest for 30 minutes.
Roll the dough out and braid into a three-stand braid.
Place in a greased 1.5lb (680g) loaf tin.
Final proof for 2 - 2.5 hours.
Glaze with egg, sprinkle with sesame seeds, and bake for 40 minutes at 160C (320F) fan on or 180C (356F) fan off.
