Preheat oven to 375 degrees F (190 degrees C).
In a small bowl, mix together the filling, click the link above.
On a lightly floured surface, roll out the dough to approximately an 11 x 15-inch rectangle. Using an offset spatula, spread the brown sugar mixture uniformly on the dough, leaving a 1/2-inch border around the edge. Sprinkle the finely chopped chocolate evenly over the mixture. Starting lengthwise, roll the dough until coiled.
Using a sharp serrated knife, cut the coil in half lengthwise and face the inside upwards. Pinch together one end of the dough and twist the two long strands, facing the cut side upwards at all times. Pinch together the remaining end. Form the dough into a circular shape. Transfer the circle to a lightly greased cast-iron pan or 9-inch round cake pan. Brush with the beaten egg and sprinkle the raw sugar evenly over the top. Bake for 25-30 minutes, or until dark brown and fragrant.
Run a knife around the outside of the pan and allow to rest for 15-20 minutes before serving.