Mornay Sauce - cooking recipe

Ingredients

1 cup white sauce
1 egg yolk
2 tablespoons cream
2 tablespoons parmesan cheese, fresh grated
2 tablespoons swiss cheese or 2 tablespoons gruyere cheese, grated
1/4 1/2 teaspoon onion juice or 1 teaspoon grated shallot
salt
cayenne pepper

Preparation

Blend the egg yolk and cream with the white sauce.
Place these ingredients into a sauce pan and bring the contents slowly to a low boil.
Whish in the cheese (s).
Remove the suace from the heat and season to taste with salt and cayenne pepper to taste.