In a bowl mix together the yeast, milk, sugar and egg. Leave for 10-15 minutes for the yeast to activate.

In the bowl of a stand mixer if you have one, or you can do this by hand, add the flour and salt.

Once the yeast mixture is frothy and bubbly add it to the bowl with the flour and salt along with the butter.

Knead the dough with a bread hook for 5-10 minutes until smooth and elastic.
Transfer the dough to an oiled bowl and cover with plastic wrap / clingfilm. Place in a warm space and leave to prove until doubled in size.

Once the dough has doubled in size Knead it again with soft hands then divide dough it out into a two part.

Take the one part add coca powder and Knead well till all coca powder incorporate well and second part leave it their Owen.
Roll out each dough into rectangle shaped and spread Nutella only white rectangle.

Then roll both white & chocolate strips into the long ropes, about 8 inches long.
Connect the top and pinch, then twist and pinch the bottom of the twist. Now, make the spiral by twirling it from the right to the left and twirl inside. At the very end, pinch from the underneath to hide it. You are left with a beautiful looking twist roll.

Allow them to rise for at least 30-40 minutes. It would be best if you allow them to rise for 60 minutes just to almost double in size.
Brush on each roll egg wash sprinkle chopped walnuts.
Preheat oven to 180°C / 356°F. Bake the rolls for 25- 30 minutes, depending on your oven, or until the rolls are golden brown and lighter when you pick them up.