Preheat the oven to 180 °C.
1. In a bowl beat together the egg whites until soft peaks form. Beat in the cream of tartar and gradually add 250 ml (1 c) caster sugar, beating well after until the sugar dissolves.
2. Sift together the flour and remaining sugar. Fold the flour mixture and a few drops of food colouring to your taste into the egg mixture, then spread in a ring cake pan. Bake for 20 minutes.