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French Mornay Sauce (Cheesy Bechamel with Gruyere)

Mornay sauce, the French culinary staple, elevates any dish with its silky béchamel base enriched by nutty Gruyère. Originating in 19th-century France, it’s named after the Mornay family, though its exact inventor remains shrouded in history. This sauce forms the backbone of classic gratins, croque-monsieur sandwiches, and decadent macaroni and cheese, offering a smooth texture that clings beautifully to pasta, vegetables, and proteins. The balance of butter, flour, and milk creates a velvety white sauce, while freshly grated cheese imparts complexity and depth. A hint of nutmeg brightens the flavors and underscores the sauce’s rich heritage in chaude cuisine. Whether you’re layering it in a vegetable gratin, drizzling it over steamed fish, or stirring it into a pasta bake, Mornay sauce adds luxurious creaminess and savory nuance to countless recipes. Its adaptability makes it a must-have in both home kitchens and professional pantries, delivering French elegance with minimal effort and maximum impact.

French | Vegetarian | Mornay Sauce | Saucepan | Whisk | All-Purpose Flour | Cow Milk | Gruyère | Unsalted Butter | Simmering | Whisking | Under 15 Minutes
Time to complete

Prep

5min

Cook

8min

Wait

0 minutes

Total

13min

Ingredients (Makes 1 cup (240 ml), serves 4)
  • 1½ tablespoons (20 g / ¾ oz) unsalted butter
  • 1½ tablespoons (12 g) all-purpose flour
  • 1 cup (240 ml) whole milk
  • Kosher salt and freshly ground black pepper, to taste
  • Freshly grated nutmeg, to taste (optional)
  • 2 ounces (55 g) finely grated Gruyère cheese
Nutrition Information (per 100g)
  • Calories: 168
  • Fat: 12.5
  • Protein: 7.4
  • Carbohydrates: 6.3
  • Fiber: 0.1
Directions

Make the Roux

  • 1. In a small saucepan, melt the butter over medium heat without allowing it to brown. Add the flour and whisk constantly to form a smooth paste. Cook, stirring, until the raw-flour scent disappears, about 1 minute.

Incorporate the Milk

  • 2. Gradually whisk in the milk in a thin, steady stream, ensuring the mixture remains smooth. The sauce will thicken and then loosen once all the milk is incorporated.

Thicken the Sauce

  • 3. Bring the sauce to a gentle simmer, whisking frequently. Reduce the heat to low and cook until the sauce coats the back of a spoon, about 3 minutes.

Season and Add Cheese

  • 4. Season with salt, pepper, and nutmeg if using. Working in two batches, whisk in the grated Gruyère, keeping the heat low to prevent the sauce from breaking.

Serve or Store

  • 5. Use immediately, or press a piece of plastic wrap directly onto the sauce surface to prevent a skin. Refrigerate up to 3 days in a sealed container and reheat gently before serving.
Cookix's Secrets

Alternative Cheeses

  • Swap Gruyère for Comté, Emmental, or a sharp white cheddar for diverse flavor notes.

Flavor Boost

  • Stir in a teaspoon of Dijon mustard or a few drops of truffle oil for a bolder flavor profile.

Gluten-Free

  • Substitute the flour with a 1:1 gluten-free flour blend or cornstarch for a gluten-free version.

Healthier Swap

  • Use low-fat milk and a reduced-fat cheese to lighten the sauce while maintaining creaminess.

Heat Control

  • Keep the heat moderate—too high and the sauce may scorch or separate once the cheese is added.

Ingredient

  • Grate the cheese finely and let it come to room temperature so it melts evenly without clumping.

Make-Ahead

  • Press plastic wrap onto the sauce surface as it cools to avoid forming a skin during storage.

Serving

  • Drizzle a little extra melted Gruyère on top of gratins before broiling for a golden crust.

Technique

  • Ensure you whisk continuously when adding milk to prevent lumps and achieve a perfectly smooth sauce.

Vegan

  • Replace butter with vegan margarine, milk with unsweetened soy or oat milk, and Gruyère with a plant-based cheese.