This white sauce is part of the filling for Rustic Pizza from The Frugal Gourmet Cooks Three Ancient Cuisines (1989)
The Frug claims that Béchamel sauce is was being used in Greece 150 years before the French were using it.
Basic White Sauce
2 cups milk
3 Tbsp. peeled and chopped yellow onion
1 bay leaf
Cayenne pepper to taste
1/2 stick butter
3 Tbsp. flour
salt to taste
Bring milk to a simmer. Add the yellow onion, bay leaf, and cayenne pepper. Simmer for a few minutes and then strain the onion and bay leaf from the milk. In another pan, melt butter, and stir in flour. Cook for just a moment and stir this into the hot milk. Return the milk to the heat, stirring constantly until it is think, about 10 minutes. Add salt to taste.
Comments: The pizza recipe calls for this sauce to be enriched with two egg yolks (you’ll use the egg whites later in the pizza filling). In this case, after you’ve added the butter-flour mixture to the milk, heat up the eggs yolks in a separate cup by slowly adding a tablespoon or two of the hot milk mixture, then pour the eggs into the milk.
Ten minutes may seem like a long time to thicken the sauce but it’s about right because you want a very thick sauce for the pizza filling.