The thing with leftovers is that you do the hamburger helper type casserole dishes AS your leftovers. In other words, you start with hamburgers, an use the extra burger patties to make the helper. And just because they call it hamburger helper doesn't mean you can't use other meats .... for example leftover chicken. Skin and bone, and instead of browning the burger, do everything else first and use the meat from the chicken (or leftover steak, roast, etc). I don't see why leftover hamburger helper couldn't be frozen though. Put it in single serving baggies or other freezer containers, then nuke for an individual lunch or dinner.
I sympathize to a degree; I learned to cook for 6, and still, after almost 40 years of doing my cooking mostly for one or two, especially when I cook something that I cook by instinct rather than recipe, it is always too much. But my husband loves leftovers, and freezing works well for most things.
I know some people won't eat leftovers at all! I'm not sure if they grew up richer than me, or with unimaginative mothers. But, really, most things do freeze well, especially casserole type dishes. A lot of meats also can be chopped and mixed into spreads for sandwiches (obviously not hamburger helper, but the chicken meat, ham, etc).
