In a large bowl of an electric mixer, combine the water and milk powder and stir until the milk dissolves. Sprinkle the yeast on top and let it sit for a few minutes.
Add the sugar, salt, butter, egg and 2 cups of the flour to the bowl. Mix on low speed with a bread dough hook (can can knead by hand) until ingredients are wet, then turn to medium speed and mix for 2 minutes. Stop the mixer and add 2 more cups of flour then mix on low speed until the ingredients are wet, then turn mixer on medium speed and mix for 2 minutes. The dough will be getting stiff and you may need to remove the bowl from the mixer and mix in the remaining flour by hand. Add approximately 1/4 cup of flour and mix until you reach a nice soft dough. The dough should be soft, not overly sticky, and not stiff. It is not necessary to use the entire amount of flour. Scrape the dough off the sides of the bowl and pour approximately one Tablespoon of vegetable oil all around the sides of the bowl. Turn the dough over in the bowl so it is covered with the oil. This helps prevent the dough from drying out. Cover with plastic and allow to rise in a warm place until double in size.
For the filling crush up chocolate chips finely (I used my blender). In small bowl mix sugars together. Once dough has doubled in size roll, sprinkle flour onto counter then put dough on flour and punch down. Roll into a large rectangle about 20 by 16 inches and 1/2 inch thick. Generously spread softened butter on top of dough, evenly covered. Sprinkle sugar mixture on top of butter then add chopped up chocolate till evenly covered. Starting on long side, roll up dough into rolled log. Cut the dough into one inch pieces with floss or a large knife. Place dough onto a buttered baking dish with rolls about 1 inch apart. Let rolls sit for about an hour or until rolls have doubled in size.
Preheat oven to 350 degrees. When rolls have risen, bake for 12 to 16 minutes, or until lightly browned. Meanwhile combine all the icing ingredients with an electric mixer and beat until smooth. Once rolls are done remove out from oven and let cool.