In a large mixing bowl, combine 2 cups of the flour, the brown sugar, yeast, and salt. Set aside.
In a small saucepan combine the evaporated milk, butter and 1/4 cup of water. Heat until the butter is almost melted and the mixture reaches 105-110 degrees on an instant read thermometer. Add the warm milk mixture to the flour mixture and add one of the eggs. Beat with an electric mixer on low speed until combined, about 30 seconds. Beat on high speed for 3 minutes. This will be a very sticky, shaggy dough. Stir in the chopped chocolate and hazelnuts.
Now add some of the remaining flour stirring with a wooden spoon until the dough is soft, but still sticky. I used the remaining 1 1/2 cups, but no more. Cover and let the dough rise in a warm place until it doubles in size (about 1 hour).
Grease a 2-quart round or square baking dish. Punch down the dough and transfer to the prepared pan. Cover and let the dough rise again in a warm place until double in size (about 1 hour).
Preheat oven to 350 degrees. In a small bowl beat the remaining egg with 1 tablespoon water until blended. Brush the egg mixture on the top of the bread then sprinkle with the turbinado (or coarse) sugar.
Bake for 50 minutes or until the loaf sounds hollow when lightly tapped. Cover the bread with foil after the first twenty minutes of baking to prevent over browning. Cool in the dish for about 10 minutes then transfer to a rack to cool completely. Serve with Nutella if desired.