Boil a large pot of salted water and cook the pasta according to the package directions. When done drain, place back in the cooking pan and add the butter.
In a large skillet sauté the tomatoes with the olive oil, 5 minutes. Remove from the heat and add the basil.
In a large bowl add the pasta, the tomatoes and mix well. Add the mozzarella and give it a last light folding.
Serve immediately