Hard-boiled eggs halved, the yolks mashed into drained tuna and tomato sauce, and the mixture spooned back into the whites with parmesan over the top. Twenty minutes, two servings.
If you have filling left over, put it in the middle of the plate: the halves hold less than the mixture makes. Cold water straight after boiling does two things: it stops the cooking, which keeps the yolks yellow instead of turning that grey-green ring around the edge, and it makes the shells come away cleanly. Ten minutes gives a fully set yolk, which is what you want here since the yolk has to mash to a paste. Cut the eggs with a sharp knife wiped clean between cuts, or the yolk drags and tears the white.