6 cups whole milk
4 1/2 cups granulated sugar
1/2 vanilla bean

Heat milk and sugar in a heavy saucepan over medium-low heat with the vanilla bean, which has been split lengthwise, scraped with the back edge of a knife and added to the milk - seeds, pod and all. When the sugar is dissolved, raise the heat to medium-high and hold between a simmer and a boil, stirring occasionally, for about 1 hour. Be sure the milk doesn't stick to the bottom of the pan. The milk will thicken, turn beige, and darken to light tan.

Strain into a bowl and cool. The milk will have reduced to 4 1/2 cups. It will keep several weeks, covered, in the refrigerator.