In a saucepan heat the milk and cream and reduce over medium heat until 2 cups remain. In a large bowl, using a whisk, beat the sugar with the egg yolks until the mixture is light and fluffy. Gradually pour the hot milk mixture into the egg mixture, whisking constantly.
Heat the mixture over simmering water, stirring constantly with a whisk or wooden spoon, until it thickens enough to coat the spoon. Make sure not to overheat or let the mixture coagulate. When thickened remove the bowl from the heat and continue stirring for a minute to ensure the mixture is uniformly cooked. Let cool to room temperature, refrigerate, covered, until completely cold, preferably overnight.
Process the mixture in an ice cream freezer following the manufacturers instructions. Serve immediately.