Potato Omelet

From 1922:

Three ounces of mealy potatoes, 2 oz. of loaf sugar, a quarter of a saltspoonful of powdered cinnamon, the strained juice of 2 oranges, three-quarters of a pint of new milk, and 3 fresh eggs.
Beat the eggs separately, and the other ingredients together, then add the eggs and beat for a quarter of an hour; fry in a small omelet pan in fresh butter till a golden color. The quantity is enough for three, and an ounce of butter for each is necessary. May be served plain or with sifted sugar, or with marmalade between. If with marmalade, the orange juice may be left out.