Separate the whites from the yolks, pour the sugar over the yolks and stir until whitened.
Add the snowy whites, mixing carefully with a spatula by stirring carefully in one direction. If you love cinnamon you can color some of the mixture with it.
Smear your form with butter, pour in the mixture and bake in a moderate oven. After baking and cooling, sprinkle the cake with powdered sugar.