Melt the butter in a saucepan over very low heat.
Separate the egg whites from the yolks. Place the yolks in a large bowl and whisk with half the sugar until pale and creamy. Add the pinch of salt to the whites and beat to stiff peaks with an electric mixer.
Mix the remaining sugar into the melted butter, then gradually pour into the yolk mixture while stirring continuously. Flavor with a few drops of orange blossom water. Gently fold in the sifted flour and beaten egg whites.
Line the special spit cake mold (*) with oiled aluminum foil and thread onto the spit. Position the spit with a dish or buttered foil below to catch dripping batter.
Spoon batter bit by bit onto the rotating spit, collecting excess in the dish. Wait for each layer to turn golden before adding more, until all batter is used.
Cool completely, unmold carefully, and serve once fully chilled.
Pair with vanilla, orange, or chocolate custard for an exquisite finish.
(*) The mold is a fluted or smooth wooden cone on a spit. Batter is layered onto the rotating cone over heat, cooking as it turns.
