In a small bowl, mix flour and vanilla powder. Set aside.
In another bowl, mix well milk, yeast, granulated sugar, egg, butter, and salt with a hand mixer with a dough hook attachments.
Add flour mixture into a wet dough, then mix it with hand mixer again until the dough is slightly sticky but not too sticky when you touch it for about 10-15 minutes.
Rise the dough for about 30-45 minutes or until doubled the size.
After the dough rises, place it on the baking mat then roll the dough for about 20 cm x 20 cm.
Spread Nutella onto the dough.
Roll the dough, then cut it using a 30 cm yarn by slide it to the bottom of the bread, then unite the two ends of the yarn as if you are going to tie it. Make 12 neatly cut roll buns.
Transfer it into a baking dish and let it rise once again for about 30 minutes. I use three 20 cm x 20 cm thin aluminum pans (4 roll buns each pan).
After 30 minutes, before you bake it, spread heavy cream on the dough in each aluminum pan.
Bake the Nutella roll buns at a temperature of 175°F until nice and golden.
When done baking, your Nutella roll buns are ready to be served. Enjoy!