Make the cocoa dough

• Mix the flour, cocoa powder, sugar, yeast and salt in a bowl.
• Add the lukewarm milk and egg, then knead into a soft dough.
• Knead in the softened butter until the dough is smooth and elastic.

Let the dough rise

• Cover the bowl and leave the dough in a warm place until doubled in size.

Shape the donuts

• Knock back the dough and divide it into equal pieces.
• Roll each piece into a smooth ball and place on a lined tray.
• Cover and prove again until puffy.

Fry the donuts

• Heat the oil to 170 °C in a deep fryer.
• Fry the donuts in batches until puffed and cooked through, turning once.
• Drain on a cooling rack and let cool slightly.

Fill the donuts

• Fill a piping bag with the Nutella.
• Pierce each donut with a skewer and pipe in the Nutella.

Coat the Ferrero donuts

• Dip the tops of half the donuts in the melted dark chocolate.
• Sprinkle with toasted chopped hazelnuts and let set.

Make the Bueno donuts

• Fill the remaining donuts with the white chocolate hazelnut spread.
• Dip them in the melted white chocolate.
• Sprinkle with crushed wafer and chopped hazelnuts and let set.