Add olive oil to a large pan over medium heat
Add cherry tomatoes, season with salt and black pepper, and cook for a few minutes
Stir, then cover with a lid and let cook another 10 minutes, until the tomatoes are soft and bursting
Mash the tomatoes gently with a wooden spoon to release their juices
Stir in the pesto and parmesan cheese and lower the heat
Add cooked spaghetti and a splash of reserved pasta water, toss until the sauce coats the pasta evenly, adding more water if needed
