The white sauce was most likely just a Bechamel, which is milk thickened with a roux. The classic recipe is:
2 Quarts Milk
1 cup All Purpose Flour
1 cup Unsalted Butter
I Whole Medium Onion
4 Cloves
2 Bay Leaves
Salt to taste
In a sauce pan, heat the milk but do not boil. In another sauce pan, over Medium High heat, melt the butter and flour while stirring using a wooden spoon, and cook until the mixture is SLIGHTLY colored but do not brown. Slowly add the milk and stir until the roux and milk is well incorporated. Stick the cloves into the onion, and add that and the bay leaves to the sauce. Bring the sauce up to a simmer, and cook for 15 minutes while stirring to prevent burning. Remove the onion and bay leaves. From this point, you can add whatever you want to flavor it with (Cheese, spices, herbs, etc.) Just make sure you heat the milk before you add it or else your sauce will be lumpy.
