 A newer method is to add liquid nitrogen to the mixture while stirring it using a spoon or spatula for a few seconds; a similar technique, advocated by Heston Blumenthal as ideal for home cooks, is to add dry ice to the mixture while stirring for a few minutes.Some ice cream recipes call for making a custard, folding in whipped cream, and immediately freezing the mixture.Another method is to use a pre-frozen solution of salt and water, which gradually melts as the ice cream freezes.