For the spaghetti sauce, first cook the pasta according to package directions.
For the sauce, sauté the onion until light brown, add the tuna without water and divide into pieces with a fork. Add the olives as well.
Whisk the cheese spread in a large cup with enough water to make it liquid (rather thick). Pour into the onion-olive-tuna mixture and let it thicken a bit more.
Serve with the pasta.