So I used to:
° 5 egg whites
° 180 grams of sugar
° 100 grams of flour
° 60 grams of butter
°60g of crushed or chopped hazelnuts
In a bowl, mix sugar, flour, melted butter and hazelnuts. I beat the egg whites. I add a few egg whites to the powder mixture to make a paste, which I then fan with the rest of the whites. I put the oven at 180 degrees for about half an hour. Mine sags a bit because I wanted to flatten them to put the lid on the mold and it was half cooked in the middle...
Appearances are deceiving, the amount of nut is not very important but it feels good! Good appetite.