I do tuna pesto pasta. It's really quick and easy and only one pan to wash.

Just cook the pasta, then drain. Into the same pan, chuck the tuna and some jarred pesto (make sure you buy a decent one, the Leggoes one is rubbish but Sacla is good).

Warm up the tuna and pesto (about 30 seconds) then return the pasta to the pan and mix. Then serve.