BISCUIT CREAM FOR MERCEDES BOMB.—Take half a pound of ratafias and half a pound of sponge biscuits, pound them together and rub through a fine wire sieve, mix the crumbs thus made with a pint and a half of cream, a wineglassful of Maraschino, a wineglassful of brandy, a saltspoonful of vanilla essence, and two ounces