Beat the eggs, salt and icing sugar in a handheld or stand mixer until they go light and fluffy and you can make a drawing on top by drizzling it and it takes a bit to go back into the mix. For further reference watch the video above.
Add the butter one tablespoon at a time with the mixer on low speed and mix until fully incorporated.
Take the bowl off the mixer and add the almond flour little by little, mixing in folding motions with a spatula, careful to not knock out the air we put into the eggs.
Pour into a buttered springform pan that has been fitted with baking paper at the base. You should also butter the sides and on top of the paper as well.
Decorate with sliced almonds on top or finely chopped. Don't toast them beforehand because the oven will do that for you.
Take it to a preheated oven at 170°C/340℉ for 30-40min or until it's golden on top. You should also be able to insert a skewer of a fine knife at the centre and it should come out clean.
Garnish with a bit of icing sugar once cold.