Slit open the vanilla beans and scrape out the seeds with a paring knife. Place about half the sugar in a double boiler; add the vanilla bean seeds and pods and milk.

In a bowl, combine the remaining sugar and egg yolks. Mix until smooth.

Over boiling water, bring the sugar, vanilla beans and milk to a high simmer, making sure all sugar is dissolved. When this mixture is very hot, add a little bit of it at a time to the yolk mixture, stirring quickly. (Add about half of the milk. This tempers the yolks so that they will not curdle when added back to milk mixture).

Now add all of the yolks to the milk over the double boiler, whisking quickly. Continue stirring constantly over the double boiler until it begins to thicken and coats a spoon like heavy cream. Remove from the double boiler.

Whisk in the cold buttermilk. Chill mixture in refrigerator until ready to freeze in ice cream machine according to manufacturer's directions. Makes about a half gallon.

Yield: 1 gallon