Beat the yolks of 9 eggs for 30 minutes with 1 lb. of sugar. Then add 1 lb. of cooked potatoes, rubbed through a sieve, a little chopped lemon peel, 30 sweet and 20 bitter almonds, finely chopped, and finally the whites of 9 eggs, beaten to a stiff snow. Work thoroughly, put the mixture in a cake tin, and place in a moderate oven till slightly brown.