Grease a large bowl and set aside.

In a stand mixer fitted with the paddle attachment, mix flour, yeast, salt, brown sugar, and cocoa powder on low speed to combine. Beat in eggs and milk. On low speed, add butter pieces, one at a time. Once all of the butter is added, increase the speed to medium and beat for 1 minute. Transfer dough to greased bowl. The dough will be very sticky and you might need to use a rubber spatula to transfer. Cover the bowl with plastic wrap and place in a warm dark place to rise.

After 30 minutes, uncover the bowl and fold the dough. To fold the dough, place your fingers under the dough and gently pull the dough up and fold it over itself. Turn the bowl and fold again. Repeat 4-6 more times, until all the dough has been folded. Cover the bowl with plastic wrap and let rise for 30 more minutes. Repeat the folding 3 more times, every 30 minute for a total rise time of 2 hours.

After the last fold, cover the bowl tightly and refrigerate overnight.

The next morning, lightly grease a 12 cup muffin pan or 12 ramekins. Alternately, you can use a 9 x 13 inch baking pan.

Flour a large work surface and roll the dough out into a 16 x 24 inch rectangle. Spread the chocolate hazelnut spread over the dough, coating it evenly. Working from the long end, roll the dough into a log, pinching the ends so it stays together. Use a sharp knife to cut the dough into 12 equal pieces. Transfer buns into prepared pan or ramekins. If using ramekins, place them on a large baking sheet.

Cover the buns and let rise once more, about 1 - 1 1/2 hours.

Preheat oven to 350 degrees F. Bake the buns for 25-30 minutes, until golden brown.

While the buns are baking, make the cream cheese icing. In a medium bowl (or bowl of stand mixer), beat all of the ingredients until fully combined.

Allow the buns to cool for 10-15 minutes. Remove from pans, then spread icing over them. Top with chopped hazelnuts.