Beat to a cream a cup of sugar and a quarter of a cup of butter, and add
to it two tablespoonfuls of wine or fruit juice, or in winter fruit
syrup. If the latter, use only three-quarters of a cup of sugar. At
serving time add a quarter of a cup of boiling water, stir well, then
add the white of an egg beaten to a stiff froth. Beat until the sauce
foams.