In a heavy bottomed saucepan heat milk, cream and sugar stirring occasionally until the sugar is dissolved and the mixture is hot. In a mixing bowl start whisking the egg yolks. Take about one cup of the hot mixture and slowly pour it into the egg yolks and keep whisking. When your egg yolk mixture is smooth, slowly pour it into your hot mixture in the saucepan, whisking constantly. Cook over medium heat, stirring constantly, until the mixture thickens and coats the back of a spoon. Be sure not to let the mixture boil at any time or it will curdle. Pass mixture through a fine strainer into a bowl and stir in the vanilla extract. Freeze in an ice cream maker according to manufacturer's instructions.