In a mixing bowl, stir together the yeast, warm milk and sugar. The milk should feel warm to the touch but not hot. Think of giving milk to a baby. Test it against your wrist if you don't have a thermometer.
Let this mixture sit for a full 5 minutes. This will allow the yeast to work!
Add 7 oz of flour to the mixture (saving the remaining flour for later)
Mix the ingredients just enough to cover all of the flour.
Let it sit for another 10 minutes.
Using a mixing bowl with a dough hook, mix the remaining 10.5 oz of flour.
Now add the butter, salt and one egg (be sure the butter and egg are at room temperature)
Mix it with a dough hook for about 4 minutes.
Place to dough in a bowl and cover it with saran wrap for about 1 hour until it doubles in size.
(Note: If you don't have a mixer you can knead the dough with your hands)
While the dough is rising. Mix together 1 cup/8 oz of Nutella with one egg. This will be the filling in your coffee cake. The egg helps it to thicken so it doesn't melt out of the cake.
Once the dough is ready, punch is down and split it into 4 or 5 different sections. This will be the layers you need.
Begin to roll each section into a circle. Use a large plate to cut an exact circle from the rolled dough.
Spread a thin layer of the Nutella mixture to the circle.
Roll out the next circle and place it on top of the previous circle. Repeat the above steps until all circles are done.
Place a cup in the center of the circle.
Use a knife and cut at the 12 o'clock hour, 3 o'clock hour, 6 o'clock hour and 9 o'clock hour of the dough.
Next, cut a line in the center of each section you cut out. Continue cutting until you have 16 equal cuts (as shown in the photos)
Remove the cup.
Grab the ends of two neighboring strips of dough and twist them outwards. Grab the next two neighboring strips and turn them outwards. Continue this step until all strips of dough are twisted.
Now twist the dough one more time and pinch the ends together on all sections to create the final design.
Now create an egg wash mixture by whipping and egg and adding 1 tablespoon of water to it. Spread this on top of the coffee cake.
Bake at 350 degrees for about 25 to 30 minutes (until golden brown)