Stir together sugar and egg yolks. Whip egg whites until stiff – remember perfectly clean whisk. Put the flour in a sieve and sprinkle it into the egg mixture, stir together until smooth. Finally, turn in the egg whites gently – first a little, then the rest with a light hand. The air must be preserved!
Set the batter with a teaspoon on baking paper on a baking sheet (or a well greased baking sheet), remember that the cakes will sag out slightly during baking. Sprinkle some sugar on each cake, and bake at 390 F / 200 C for about 10 min. on the middle shelf in the oven (conventional top and bottom heat). The cakes should be slightly golden, check often. Don’t put the cookies in a cake tin before they have not only cooled but are dry enough to break in two – then they will tastes the best!
A tip from “Housekeeping for Town and Country” by Marie Blom, 1888: “All dough which eggs as main component, must not stand, but be baked immediately; even worse be left on the baking sheets when finished. Cool on a rack!