Heat the milk until hot in a separate container, either in the microwave or on the stove.
For the béchamel base, melt the butter and add the flour. Cook over medium-high heat for about 30–60 seconds to cook off the flour’s raw taste. Keep the flour pale.
Pour the hot milk into the butter-and-flour mixture all at once and stir very quickly. Season with salt and white pepper.If you’ve done it right, this method gives you a lump-free béchamel. But you can always blend it with an immersion blender for a completely smooth consistency.
Bring to a boil while stirring, then cook over low heat for about 5 minutes. If it’s too thick, thin it with a little milk.
Remove from the heat and stir in the finely chopped fresh parsley.