Easy Chocolate Babka

In a large bowl or stand mixer fitted with the dough hook attachment, beat together the warm milk, butter, eggs, sugar, yeast, and salt. Gradually beat in the flour and mix until a smooth dough forms, about 6-7 minutes. If the dough is too sticky, add a bit more flour, but be careful not to add too much.
Transfer the dough to a greased bowl, cover with plastic wrap, and let rise for 90 minutes (or until doubled in size). I usually place the dough in my oven with the light on.
This recipe makes two loaves. Cut the dough in half and set one half aside while you make the first babka. Roll the dough into a 9x13 inch rectangle. Spread 1 cup of Nutella all over, except for ½ inch around the border. Roll up tightly into a log and rest on its seam. Use a sharp knife and cut the log in half LENGTHWISE. Place one half of the log, cut side down, on top of the other half, making an "X" shape. Then, twist the two pieces together.
Transfer to a greased loaf pan and repeat with the other half of the dough.
Let shaped dough rest for 30-35 minutes. In the meantime, mix together the brown sugar, flour, and cinnamon. Use two knives or a pastry cutter to cut in the butter to form the crumble topping.
Preheat your oven to 350°F. Brush both loaves with the egg wash and sprinkle with the crumble topping.
Bake for 40-45 minutes until golden brown on top. Remove from the oven and allow them to cool in the pan for 10 minutes before serving. Enjoy!