Cook pasta according to the package directions.
While pasta is cooking, chop the onions and cut the cherry tomatoes in halves.
Add olive oil to a medium-large pan, and heat for 2 min. in medium heat.
Add onions to the pan and sauté until transparent.
Add tomatoes and cook for 2 min. or until tender.
When pasta is cooked, save some of the pasta water when draining. This water will be used for diluting the pesto sauce.
Add basil pesto sauce to the pan. Mix well, add some of the pasta water just enough to dilute the pesto and to make it saucy.
Heat through for about a minute while mixing the pasta. Add more pesto sauce if desired. Add more pasta water if mixture is too thick.
Serve the tomato and pesto pasta on bowls, garnish with basil leaves, and enjoy!
Pair it with a salad and/or garlic bread if desired.