Heat the butter in a medium-size saucepan over medium heat. Add the flour and whisk until smooth. Cook, stirring, until golden brown, about 6 to 7 minutes. In a separate pan, heat the milk until just about to boil, and then add it to the butter mixture, 1 cup at a time, whisking constantly until very smooth. Bring to a boil and cook 30 seconds longer. Remove from the heat and season with salt and nutmeg.
Yield: 2 cups