The day before: In a small bowl, dissolve the yeast and
Sift the flour into a large bowl, then stir in the salt. Add the yeast mixture, eggs, remaining sugar and butter, and beat everything until well mixed. Leave the dough in a warm place for about 2–4 hours, or until doubled in size.
Push down the dough with a wooden spoon, then put it in a greased clean bowl, cover with cling film and leave overnight in a cool place.
In the morning, butter a large brioche or kugelhopf mould. Break down the dough and knead it briefly until all the air has been squeezed out. Knead in the cocoa nibs, then put the dough into the buttered mould and cover with cling film. Leave in a warm place for about 3–4 hours, or until the dough rises to the top of the mould (i.e. doubles in size).