This was Andrea's contribution to the pool of "let's do something easy" ideas.
I did my standard preparation: mix tuna with minced onion, garlic, mustard, and mayo; stir that into some mostly-cooked elbow macaroni along with some milk (and a bit of frischkase, because it was there), pour into an oiled dish and then top with grated cheese (gruyere). I did an extra layer of grated cheese mixed with raclette spice and bread crumbs to ensure crunch. This got baked until it was done.
We ate this with a green salad