METHOD
1. Separate the egg yolks from the whites.
2. Using a hand blender, whisk the egg yolks, sugar and vegetable oil until creamy.
3. Whisk the egg whites until stiff peaks form.
4. Carefully fold the egg whites into the egg yolk mixture, then sift the flour and fold this into the mixture.
5. Divide the mixture into 2 portions and mix one with the cocoa powder and the other with the cornflour.
6. Pour the white half of the mixture onto a baking tray lined with parchment and spread evenly.
7. Bake for 5 minutes at 190°C/375°F.
8. Pour the chocolate mixture over the base layer and spread evenly. Bake for 8 minutes.
9. Leave the roll to cool, remove the baking paper and spread the hazelnut cream over the base of the cake. Roll up well and leave to firm up in the fridge.
10. Carefully slice the roll and dip each slice in the melted chocolate, covering one side.
