Recipe may be doubled, but no more. Melt butter in top of double boiler over simmmering water. Stir in sugar until lump-free and smooth, stir in oatmeal, then egg. Cook dough uncovered, 1 hour over bareluy simmering water, stirring occasionally.Remove top of double boiler from heat, add vanilla and let dough stand at room temperature 1 hour, to firm. ( dough is quite runny when hot.) Preheat oven to 180ºC . Cover cookie sheets with foil, set aside. drop dough by level quarter teaspoonful, 1 cm apart. Bake 7 minutes or until well-browned. Cool to lukewarm, when cookies will peel away from foil. Store in tightly covered container, with padlock, if desired. Makes a little over a pound, about 200 tiny cookies, of 10 calories each. ----