Mix the egg white with the hazelnuts, the flour, the sugar, the salt and the zest from the lemon. Blend it till smooth, this takes at least 2 to 3 minutes.
Once smooth pass it through a fine sieve to insure there are no lumps. Pass it through using a ladle so you don’t waste a single drop.
Now pour the batter into a siphon and charge it with 2 charges. Shake it well after each charge for a beautiful fluffy sponge cake.
Then make 3 thin slices in some paper cups and place them next to each other. Fill the cups a little over half and then bake the sponge cakes at 600 watts for 40 to 45 seconds.
Once baked turn the cups upside down on your worktop and let them cool down completely.
Now to remove the cakes give the cups a quick roll and then turn them around on your worktop. If they stick you can always give them a little hand with a knife. Then keep them covered in your fridge for later.
