In a large pot, cook the pasta until al dente in salted water according to the instructions on the package.
While the pasta is cooking, in a food processor pulse the olives and walnuts with the olive oil until finely chopped. Add the mint and pulse until you get a paste. Crumble most of the feta and set aside.
Once the pasta is cooked, drain it but set aside about half a cup of the pasta water.
Heat a large pan. Add the pasta to the pan with the olive and mint pesto, add most of the feta and the pasta water. Mix well together and let cook until everything is combined and creamy. Add the cherry tomatoes and a couple of whole pitted olives and mix well.
Serve immediately, with some crumbled feta on top.