Ingredients
1 1/2 tablespoons unsalted butter (3/4 ounce; 20g) (see notes)
1 1/2 tablespoons (12g) all-purpose flour (see notes)
1 cup (240ml) whole milk
Kosher salt and freshly ground black pepper
Freshly grated nutmeg, to taste (optional)
Directions
1
In a small saucepan, melt butter over medium-high heat (do not allow it to brown). Add flour and whisk to form a paste. Continue to cook, stirring, until raw flour scent is gone, about 1 minute. Whisking constantly, add milk in a thin, steady stream, or in increments of a couple of tablespoons at a time, whisking thoroughly and getting into all corners of the pan to maintain a homogeneous texture. Sauce will initially become very thick, then get very thin once all the milk is added.
2
Heat, stirring, until sauce comes to a simmer and begins to thicken slightly. Reduce heat to low and cook, stirring, until sauce is thick enough to coat the back of a wooden spoon, about 3 minutes.
3
Season with salt and pepper. Add nutmeg to taste, if using. If any lumps form, simply whisk thoroughly to remove them and smooth out sauce, or use a hand blender or countertop blender if lumps are particularly large or tough. Use sauce right away, or press a piece of plastic wrap over surface of sauce to prevent a skin from forming and keep warm until ready to use. Sauce can be cooled and stored in a sealed container in the refrigerator for several days. Reheat very gently on the stovetop or in a microwave to use.
Notes
This recipe uses a ratio of 1 1/2 tablespoons each of flour and butter per cup of milk, producing a sauce that's luxuriously silky and thick, but still quite pourable—it will work well in a variety of dishes. Depending on the recipe and your personal preference, you can make a thinner béchamel by reducing the flour and butter to 1 tablespoon each per cup of milk, or a very thick one (say, for a soufflé base or Greek moussaka) by increasing them to 3 tablespoons each per cup of milk. You can easily scale this recipe up or down as desired.