I'm not sure what green beans to use ... frozen, fresh or canned, so I just used what I had ... 1 14 oz. can of cut green beans. I heated them in the microwave for a couple minutes before putting them in the saucepan. I omitted the tomatoes b/c none of us like them. The cheese slices and bit of milk made an excellent cheese sauce, and the oregano was a perfect complement. Easy, fast, and turned out good. The kids even enjoyed it!