Cheese Sauce Recipe

Make a roux

In a medium saucepan over medium heat melt the unsalted butter. When it foams and the butter solids begin to sizzle (about 1 minute), add the all-purpose flour and whisk constantly for 1 to 1 1/2 minutes to cook the raw flour taste but not brown the roux.

Add dairy

Gradually whisk in the whole milk and half-and-half in a slow stream, whisking constantly to keep the mixture smooth. Bring the mixture to a gentle simmer over medium-low heat, whisking, until it thickens enough to coat the back of a spoon (about 3–5 minutes). Reduce heat to low.

Optional slurry for stability

If you plan to reheat the sauce or want extra stability, stir the cornstarch into the cold water to make a smooth slurry. Whisk 1 teaspoon cornstarch slurry into the simmering béchamel and cook 1 minute to activate the starch before adding cheese.

Temper and add cheese

Remove the thickened milk mixture from direct heat (keep it warm on the turned-off burner) and add the grated cheeses in small handfuls, whisking or stirring gently after each addition until just melted and fully incorporated. Do not boil after adding cheese or it may seize and become grainy.

Season and finish

Stir in the Dijon mustard, Worcestershire sauce, ground black pepper, salt, and cayenne (if using). Taste and adjust seasoning. If the sauce is too thick, whisk in up to 2 tablespoons warm milk to reach desired consistency. Keep the sauce warm over very low heat or a double boiler, stirring occasionally until serving.

If the sauce becomes grainy or slightly separated, remove from heat and whisk in 1–2 tablespoons warm milk or a teaspoon of hot water vigorously to bring it back together. Strain through a fine-mesh sieve if necessary for an ultra-smooth finish.