Follow these steps to create delicious Chocolate Nutella Rolls:

1. Prepare Dough: In a large mixing bowl, combine 3 cups of flour, sugar, yeast, and salt. Mix well.
2. Mix Wet Ingredients: In a separate bowl, whisk together the warmed milk, melted butter, and eggs.
3. Combine Mixtures: Pour the wet ingredients into the dry ingredients and mix until combined. Gradually add the remaining cup of flour until a dough forms.
4. Knead Dough: Knead the dough on a floured surface for about 5-7 minutes until it’s smooth and elastic.
5. First Rise: Place the dough in a lightly greased bowl, cover with a cloth, and let it rise in a warm place for about 60 minutes, or until doubled in size.
6. Prepare Filling: Once the dough has risen, punch it down and roll it out on a floured surface into a large rectangle (about 16×24 inches).
7. Spread Nutella: Evenly spread Nutella across the surface of the dough, leaving a small border for sealing the rolls.
8. Add Hazelnuts: If using, sprinkle the chopped hazelnuts over the Nutella.
9. Roll Dough: Starting from one long side, tightly roll the dough into a log shape, being careful not to squish out the filling.
10. Slice Rolls: Using a sharp knife, slice the log into 12 equal pieces.
11. Prepare for Second Rise: Place the rolls cut-side up in a greased baking dish, allowing some space between them.
12. Second Rise: Cover with a cloth and let the rolls rise again for about 30 minutes.
13. Preheat Oven: While the rolls rise, preheat your oven to 350°F (175°C).
14. Egg Wash: Brush the tops of the rolls with the beaten egg for a golden finish.
15. Bake: Bake the rolls in the preheated oven for 25-30 minutes, or until golden brown.
16. Cool Slightly: Once baked, allow them to cool in the pan for about 10 minutes before transferring them to a wire rack.
17. Dust with Powdered Sugar: If desired, dust with powdered sugar before serving.

These straightforward steps will help you achieve the perfect Chocolate Nutella Rolls with each and every bake!