Mornaise Sauce

Mornay sauce is a French mother sauce built on a white bechamel base, enriched with egg yolks, cream, and Swiss cheese. This version uses the microwave to melt the butter and build the roux, making the whole process faster and nearly foolproof.

The technique follows classic French steps in miniature. Melt butter, stir in flour until smooth to form the roux, then gradually whisk in milk. The egg yolks get beaten with the cream first, then tempered with the hot sauce before going back in. The cheese goes in last, off the heat, so it melts gently without breaking or turning grainy.

This sauce is the foundation for so many dishes. Pour it over steamed vegetables, spoon it into a croque monsieur, use it as the base for a gratin, or blanket a pan of eggs Benedict.

Pro Tips

• Add the milk gradually to the roux, whisking constantly. Adding it all at once creates lumps that are hard to smooth out.
• Temper the egg yolks by adding the hot mixture slowly while whisking. Pouring hot liquid into cold yolks too fast will scramble them.
• Add the Swiss cheese at the very end and stir until just melted. Too much heat after the cheese goes in makes the sauce oily and stringy.
• If the sauce is too thick, thin it with a splash of warm milk.

Variations

• Use Gruyere instead of Swiss for a nuttier, more complex cheese flavor.
• Add a pinch of nutmeg and a dash of cayenne for the traditional French seasoning.
• Stir in Parmesan alongside the Swiss for a sharper, more savory sauce.