In a small bowl dissolve both packages of yeast in warm water. Let it sit for a couple of minutes.
In a large bowl combine egg, butter, sugar, salt, yeasted water and 3 cups of flour. Mix until well combined.
Add the rest of the flour to make very soft dough. Mix quickly but do not knead. The dough will be sticky. Cover with plastic wrap and leave overnight in the fridge.
In the morning turn out the dough on a well-floured surface and divide into two, roll into balls. Cover one ball with a tea towel to prevent drying out while you working on the other one.
With a rolling pin roll the dough into a rectangle 18X12", spread with ¼ cup of Nutella leaving ½" border and sprinkle with ¼ cup of ground almonds.
Roll tightly starting from the long side. Pinch seam to seal and place on a cutting board seam side down. Slice into 12 pieces and arrange them on a well-oiled 13X9 baking pan. Cover with a tea towel and let it rise for 1 hour in a warm place. Repeat the same process with the remaining dough. Bake in the preheated oven at 375 F/ 190C for 25 minutes.
While the rolls are baking prepare the glaze. Split a vanilla bean lengthwise with a sharp knife and scrape out vanilla seeds. In a small bowl mix icing sugar with milk, almond extract and vanilla bean seeds. Drizzle over warm out of the oven rolls. Sprinkle with chopped chocolate if desired.