Béchamel sauce

From Mark Bittman's How to Make Everything

• 2 tablespoons butter
• 2 tablespoons flour
• 1 1/2 cups milk

1. In a small saucepan, heat the butter over medium-low heat. When the foam begins to subside, stir in the flour. Turn the heat to low and cook, stirring with a wire whisk almost constantly, until the flour-butter mixture darkens, at least 3 minutes. You can cook it longer if ou would like a darker color and slightly more complex flavor.
2. Stir in the liquid, a little bit at a time, still using the whisk. When about a cup of the liquid has been stirred in, the mixture will be fairly thick. Add more liquid, a little at a time, until the consistence is just about a little thinner than you like, then cook, still over low heat until the mixture is the thickness you want.
3. Season to task and serve immediately or keep warm over gently simmering water for up to an hour, stirring occasionally.