Green Onion-Parmesan Mornay Sauce
Melt butter in a heavy saucepan over medium heat. Stir in green onion and parsley; cook until the green onion has softened, about 3 minutes. Stir in flour and cook for 3 minutes more, stirring constantly.Advertisement
Pour in the cream, increase heat to medium-high and bring to a simmer. Once the cream comes to a simmer, reduce heat to medium-low and whisk in the shredded Swiss and Parmesan cheeses. Slowly simmer, uncovered, until the sauce has thickened, about 3 minutes. Season to taste with salt and pepper before serving.