Cook the pasta in salted water according to package instructions till al dente. While the pasta is cooking, reserve ½ cup pasta water and set aside.
Heat oil in a pan and add garlic. Sauté the garlic for 2-3 minutes.
Add tomatoes and cook them for a few minutes till soft. Break the tomatoes slightly with the back of a spoon. Season with some salt.
Add reserved pasta water and simmer for 5 minutes till it thickens and becomes saucy.
Add pasta and butter and toss well. Add the basil, toss again till the basil wilts.
Serve immediately.