In the bowl of a stand mixer, add the sugar, instant yeast, salt and flour and mix to combine. Add the remaining ingredients, warm milk, melted butter, sourdough discard and the egg. Knead with the dough hook attachment for about 8-10 minutes or until a smooth ball forms.

Dump the dough onto a lightly floured work surface and divide into four equal pieces. If the dough is really sticky sprinkle on a little more flour.

Roll out one section in roughly 10 inch diameter circles. Set aside and repeat with the remaining 3 sections.

Place one piece of dough down on the silicone mat or on a piece of parchment paper. Spread ⅓ cup of Nutella evenly over the dough. Place another piece of dough on top and spread another ⅓ cup of Nutella on top. Repeat one more time.

Place a shot glass or small mason jar ring in the center of the dough. Begin by cutting the dough into 4 equal sections, stopping at the cup so the center stays intact. Then cut each section into an additional 4 equal sections. Use a sharp knife or a pizza cutter to easily cut the dough into equal strips. Now you should have 16 cuts around the dough.

Take 2 strips of dough and twist them in opposite directions two or three times. Squeeze the ends together. Repeat this 7 more times.

Place the star bread on a sheet pan and cover it with a lid or foil. Let the dough rise at 85°F for 1 hour or until the star bread has increased in size and is puffy.

Preheat the oven to 350ºF. Make an egg wash with one egg and a teaspoon of water. Brush it on top of the star with a pastry brush.

Bake covered with foil for 15 minutes, then uncover and bake for an additional 10-15 minutes until lightly browned and the internal temperature reaches 190ºF. Remove from the oven and sprinkle with a dusting of powdered sugar if desired. Serve warm.