This is the version of tuna casserole that my mom made while I was growing up. I loved this stuff, and never understood why people made fun of it. Once I got a little older and tried some of the "standard recipes" it suddenly made more sense why tuna hotdish was so despised: Cream of mushroom or onion soup as part of the white sauce!
Mom's version is made with a sauce consisting of milk, flour and mayo. In my opinion, this gives the dish a much better flavor.