Mornay Sauce

• 2 tablespoons unsalted butter
• 1/4 cup finely chopped onion
• 1 tablespoon all-purpose flour
• 1 1/2 cups whole milk
• 1/4 teaspoon salt
• Dash of freshly ground white pepper
• Freshly grated nutmeg (optional)
• 1/2 cup (2 ounces) shredded Gruyere cheese

1. Place butter in a small saucepan over medium-low heat; cook until butter melts, stirring occasionally. Add onion to pan; cook 10 minutes or until tender (do not brown), stirring occasionally. Sprinkle flour over onion; cook 2 minutes, stirring occasionally.
2. Gradually add milk to flour mixture, stirring with a whisk until smooth; bring to a simmer. Simmer 10 minutes or until thickened, stirring frequently. Strain mixture through a fine sieve over a bowl; discard solids.
3. Stir in salt, pepper, and nutmeg, if desired.
4. Wipe pan clean with paper towels. Return sauce to pan, and place over medium-low heat. Add Gruyere cheese, stirring until smooth. Serve immediately.

unsalted butter, onion, flour, milk, salt, ground white pepper, nutmeg, gruyuere cheese

Taken from www.myrecipes.com/recipe/mornay-sauce-2 (may not work)