Heat a small pot of water with the butter, peeled onion, and some salt. When boiling, add the pasta and cook until tender. Drain.

While the water is heating, open and drain the tuna and shred with a fork, set aside.

Heat the olive oil in a non stick pan on low heat, when hot, add the diced onion, cook, stirring often until the onion starts to turn golden brown.

Then add the tuna and season with pepper, rosemary, and oregano as desired and cook for a few minutes to heat the tuna through.

Add the drained pasta and cream, toss everything together and cook for a few minutes to heat everything through.

Remove from heat, serve, and enjoy.