Instructions

1. In a small bowl or liquid measuring cup, stir the yeast and sugar into the warm milk. Allow mixture to rest and become foamy and frothy, about 5 minutes. Whisk in the egg yolk and melted butter to the yeast mixture.
2. In the bowl of a large stand mixer, stir together the flours and salt.
3. Using the dough hook with the stand mixer running on low, gradually pour in the wet ingredients. Increase the speed to medium and knead until the dough becomes smooth, but still soft and damp. Shape dough into a ball, place in an oiled bowl, and then cover. Allow to rise at room temperature until doubled in size, about 1-1 1/2 hours.
4. While dough rises, prepare filling. In a small bowl, combine the chocolate, coconut sugar, and cinnamon.
5. Grease a 10-inch cast iron skillet or a 9-inch cake pan. On a lightly floured surface, roll dough into a 18 x 12-inch rectangle. Spread butter evenly on dough. Sprinkle filling evenly over the butter, leaving a 1-inch border around the edges. Carefully roll up length-wise and pinch the edges together to seal. Using a sharp knife, cut log in half length-wise. Pinch two ends together and then twist the bread by gently lifting one strand over the other strand until you reach the end of the log. Form a circle and pinch the ends together to connect.
6. Allow bread to rise again until an indentation remains after touching, about 45 minutes.
7. About halfway through the second rising, preheat the oven to 375.
8. When bread is ready to be baked, lightly brush with egg wash. Bake for 20-25 minutes, until light golden brown. Cool for 30 minutes and dust with powdered sugar if desired. This is best served slightly warm out of the oven.