Chill the Nutella

• Place the Nutella in the refrigerator so it firms up.

Make the dough

• Combine the flour, sugar, dry yeast, salt, egg, vanilla sugar and lukewarm milk in a bowl.
• Knead the dough for 5 minutes.

Add butter and chocolate chips

• Add the softened butter and knead again for 5 minutes.
• Work in the chocolate chips.

Let the dough rise

• Cover the dough and let it rise until doubled in volume.

Shape the buns

• Divide the dough into portions and flatten each one.
• Place a spoonful of chilled Nutella in the center and seal the dough around it into a ball.
• Arrange the buns on a lined baking tray.

Brush with egg wash

• Mix the egg yolk with the milk and brush the buns.

Bake

• Bake in a preheated oven at 180 °C until golden.