Creamed Tuna on Toast

I learned this recipe from watching my mom make it. I remember having this dish after I came home from the hospital after having my tonsils out.

Melt some butter (about 2 to 3 tsps).
Add some flour (about a tablespoon or a bit more).
Cook over low heat, stirring for several minutes.
Add can of drained tuna. Break tuna apart.
Add a cup of milk.
Stir and cook over medium heat until the sauce is thickened. If too thick, add a bit more milk.

This is really a simple white sauce (bechamel) with tuna tossed in so any recipe book would have a more accurate recipe for the sauce.