make a bechamel sauce:
* 5 tablespoons butter
* 4 tablespoons all-purpose flour
* 4 cups milk
* 2 teaspoons salt
* 1/2 teaspoon freshly grated nutmeg
Directions
In a medium saucepan, heat the butter over medium-low heat until melted. Add the flour and stir until smooth. Over medium heat, cook until the mixture turns a light, golden sandy color, about 6 to 7 minutes.
Meanwhile, heat the milk in a separate pan until just about to boil. Add the hot milk to the butter mixture 1 cup at a time, whisking continuously until very smooth. Bring to a boil. Cook 10 minutes, stirring constantly, then remove from heat. Season with salt and nutmeg, and set aside until ready to use.
If you like, you can then add mushrooms for cream of mushroom. I use this as a base for my tuna casserole (no nutmeg though) at it is much better than using cans, which I almost never do anymore.