Dulce de Leche (Sweet Milk)

This makes a wonderful topping for vanilla ice cream, for custard, or for yellow cakes and even fruit. But it is so wonderful you may want to eat it straight from the pan.

5 cups whole milk
1 1/2 cups granulated sugar
1 vanilla bean, split
1 teaspoon baking soda

Put the milk in a large, heavy saucepan over medium-high heat. Bring to a boil and allow skin to form on top. Do not stir. The skin will thicken and puff up. After this, reduce the heat to medium and remove the skin. Increase the heat to medium-high and repeat the process 3 times.

Add the sugar and vanilla bean, and stir until the sugar has melted, about 2 minutes. Reduce heat to low and stir in the baking soda. Simmer milk, stirring often, but taking care not to break the film of cooked milk forming on the inside of the pan. Keep simmering, skimming the foam (which is different from the film) until reduced by half, about 1 hour. Turn the heat down even lower and simmer for another 3 and 1/2 hours, stirring and skimming foam occasionally. The mixture will brown as it cooks. Strain the completely cooked mixture through a sieve into a bowl, then cover and refrigerate, which will thicken it even more. Makes about 1 1/2 cups.