- Using a tabletop mixer, start whipping the egg whites and progressively add the sugar #2, followed by the cream of tartar.
- Combine the eggs, the egg yolks, the sugar #1 and the hazelnut flour in a mixing bowl.
- Scrape the vanilla beans and add them into the mixing bowl.
- Whip the mixture until well combined.
- Add the sifted flour and incorporate the melted butter.
- Fold the whipped egg whites into the mixing bowl and transfer the mixture into a piping bag.
- Pipe 1 cm (0.4”) of batter into the greased cake rings.
- Bake at 160°C (320°F) for 18-20 minutes.
- Using a knife, unmold the biscuits and reserve in the fridge.