In a large mixing bowl, combine 1 cup of warm milk, 2 tablespoons of sugar, and yeast. Stir gently and let sit for 5-10 minutes until foamy.
In a separate bowl, whisk together the flour, remaining sugar, and salt.
Once the yeast is activated, add the melted butter and eggs to the yeast mixture. Gradually add the dry ingredients until a dough forms.
Turn the dough onto a lightly floured surface and knead for about 5-7 minutes until smooth and elastic.
Place the dough in a greased bowl, cover with a kitchen towel, and let it rise in a warm place for 1-2 hours or until doubled in size.
After the dough has risen, punch it down and roll it out on a floured surface into a large rectangle (approx. 16x24 inches).
Spread an even layer of chocolate hazelnut spread over the dough, leaving a small border around the edges. Sprinkle cocoa powder and chopped hazelnuts on top.
Starting from one long side, roll the dough tightly into a log. Pinch the seams to seal.
Cut the rolled dough in half lengthwise. Twist the two halves together, keeping the cut sides facing up.
Transfer the twisted dough into a greased loaf pan. Cover and let rise for another 30-45 minutes.
Preheat your oven to 350°F (175°C).
Beat the extra egg and brush it over the top of the babka.
Bake for 30-35 minutes or until golden brown and a toothpick inserted into the center comes out clean.
Allow to cool in the pan for 10 minutes, then transfer to a wire rack. Dust with powdered sugar if desired before slicing.
Notes
Dust with powdered sugar before serving for an extra touch.