📝 About This Recipe
A sophisticated evolution of the classic Béchamel, Sauce Mornay is the quintessential French cheese sauce, enriched with nutty Gruyère and sharp Parmesan. This silky, ivory masterpiece dates back to the 19th century and is celebrated for its ability to transform simple vegetables, seafood, or eggs into a luxurious feast. Its rich, velvety texture and complex savory notes make it a cornerstone of haute cuisine and the secret to the perfect Gratin.
🥗 Ingredients
The Roux Base
- 3 tablespoons Unsalted Butter (high-quality European style preferred)
- 3 tablespoons All-Purpose Flour (sifted)
The Liquid Infusion
- 2 cups Whole Milk (warmed slightly to prevent clumping)
- 1 thick slice Yellow Onion (for aromatic infusion)
- 1 Whole Clove (pinned into the onion slice)
- 1 Fresh Bay Leaf (small)
The Cheese & Seasoning
- 1/2 cup Gruyère Cheese (finely grated, aged at least 6 months)
- 1/4 cup Parmigiano-Reggiano (freshly grated)
- 1 large Egg Yolk (tempered for extra richness)
- 2 tablespoons Heavy Cream (at room temperature)
- 1/2 teaspoon Kosher Salt (or to taste)
- 1/4 teaspoon White Pepper (ground, to maintain the white color)
- 1 pinch Nutmeg (freshly grated is essential)
- 1 tiny pinch Cayenne Pepper (optional, for a subtle back-note of heat)
👨🍳 Instructions
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1
Begin by warming your whole milk in a small saucepan over low heat. You don't want it to boil; just bring it to a gentle simmer to ensure a smooth incorporation with the roux later.
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2
In a heavy-bottomed saucepan over medium-low heat, melt the 3 tablespoons of unsalted butter until it begins to foam slightly.
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3
Whisk in the sifted flour to create your roux. Cook this mixture for 2-3 minutes, whisking constantly. You are looking for a 'white roux'—it should smell slightly nutty but must not take on any brown color.
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4
Slowly begin adding the warm milk, about 1/4 cup at a time. Whisk vigorously after each addition until the liquid is fully incorporated and the mixture is smooth before adding more.
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5
Once all the milk is added, drop in the onion slice (with the clove pinned to it) and the bay leaf. This is a classic French technique for subtle aromatic depth.
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6
Simmer the sauce gently on low heat for about 10 minutes. Stir frequently with a wooden spoon, ensuring the bottom doesn't scorch. The sauce should thicken enough to coat the back of the spoon.
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7
Remove the onion, clove, and bay leaf from the sauce and discard them.
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8
In a small bowl, whisk together the egg yolk and the heavy cream to create a 'liaison'. This will provide the sauce with its signature velvety finish.
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9
Temper the egg mixture by slowly whisking in two tablespoons of the hot sauce into the bowl, then pour the tempered mixture back into the main saucepan while whisking constantly.
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10
Turn the heat to the lowest setting and stir in the grated Gruyère and Parmigiano-Reggiano. Stir until the cheese is just melted and the sauce is glossy. Do not let the sauce boil after the cheese is added, or it may become grainy.
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11
Season the sauce with kosher salt, white pepper, a fresh grating of nutmeg, and a tiny pinch of cayenne.
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12
Taste and adjust seasoning. If the sauce is too thick, thin it with a tablespoon of warm milk. Serve immediately while warm and flowing.
💡 Chef's Tips
Always grate your own cheese from a block; pre-shredded cheeses are coated in potato starch which will make your sauce gritty. If your sauce develops lumps, don't panic—simply pass it through a fine-mesh sieve (chinois) before adding the cheese. To prevent a skin from forming on the surface if not serving immediately, press a piece of plastic wrap directly onto the surface of the sauce. For a lighter version, you can substitute Emmental for Gruyère, but avoid using high-moisture cheeses like mozzarella which change the texture significantly. Never boil the sauce once the cheese is added, as the proteins in the cheese will tighten and separate from the fats, ruining the emulsion.
🍽️ Serving Suggestions
Drizzle generously over steamed asparagus or cauliflower for a classic vegetable gratin. Use as the decadent base for a Croque Monsieur sandwich or the crowned Croque Madame. Fold into cooked macaroni for the most luxurious Macaroni and Cheese you have ever tasted. Serve over poached eggs and toasted English muffins for a 'Mornay' twist on Eggs Benedict. Pairs beautifully with a crisp, dry white wine like a Chablis or a Sancerre to cut through the richness.