In a large pot of boiling water, quickly submerge and remove the tomatoes. Peel them, remove the seeds, and chop into bite sized pieces. Place the tomatoes in a large bowl, and add the olive oil, basil, garlic, salt and pepper. Mix gently, cover, and let rest for 30 minutes.
Bring a large pot of salted water to a boil. Cook the spaghetti until al dente, drain it, and add to the tomatoes. Sprinkle with Pecorino and serve immediately.