In a large microwave-safe bowl, melt the butter for about 1 minute on high power, until fully melted and bubbling. Let it cool for a quick moment.
Add flour:
Add the flour to the melted butter. Stir vigorously with a whisk until the mixture forms a smooth paste (a roux) with no lumps. This helps create a silky sauce.
Turning the liquid in:
3) Heat the milk:
In a separate saucepan or microwave-safe container, heat the milk to just under a boil. You’ll see gentle bubbles around the edges. Do not boil vigorously.
Combine:
Slowly pour the hot milk into the flour-butter mixture while whisking constantly. Start with a small amount to loosen the paste, then gradually add the rest. Continue whisking until the mixture is smooth and free of lumps.
Seasoning:
5) Season and finish:
Add salt and pepper to taste. If using nutmeg, grate a tiny pinch into the sauce for a classic touch.
Optional quick reheat (microwave method):
Return the sauce to the microwave and heat for about 1 minute on high, stopping halfway to whisk. This helps it reach a creamy, uniform texture.
Final whisk and serve:
7) Whisk again:
