In the bowl of an electric mixer, combine 1 cup of flour with the sugar, salt, and yeast, and set it aside.

In a small saucepan, mix the buttermilk, water, and butter, heating over low until the mixture reaches about 125°F; the butter may not fully melt.

Pour the warm liquid mixture into the flour mixture and beat on medium speed for 2 minutes.

Add the egg and ½ cup of flour, then beat on high speed for another 2 minutes.

Gradually stir in the remaining flour until a dough forms, being careful not to overmix.

Cover the dough with a kitchen towel and let it rest for 20 minutes.

Transfer the dough to a well-floured surface and knead it a few times, then roll it out into a rectangle approximately 10"x18".

Visualize the dough divided into thirds lengthwise and spread the Nutella across the center third.

Make diagonal cuts about 1 inch apart on either side of the filling, stopping ½ inch from the center.

Starting from the top, braid the dough by alternating the strips over the filling.

You can either bake the loaf as is or form it into a ring by joining the ends together and pinching them to seal.

Place the braided dough on a baking sheet lined with parchment paper or a silicone mat.

If making a ring, lightly spray or brush a piece of parchment paper with baking spray and cover the dough, ensuring the oiled side touches the dough.

Cover the entire baking sheet with plastic wrap and refrigerate for at least 2 hours or overnight.

Preheat the oven to 375°F and let the dough rest at room temperature for 10 minutes before baking.

Bake for 25-30 minutes, or until the bread is golden brown.

In a small bowl, whisk together the confectioners' sugar, melted butter, vanilla, and milk.

Once the bread is golden, remove it from the oven and let it cool on a wire rack before drizzling with the sugar glaze.

This bread is best enjoyed warm.