Put a pot with water on the stove. When it boils, cook the pasta and add a pinch of salt. Meanwhile, pour the oil, the spring onion and the pancetta into a pan and brown them. Then add the tomatoes and continue cooking for a few minutes. Once the pasta is cooked, drain the water, put the pasta into the pan with the other ingredients so that all flavours combine together and finish the dish adding Parmigiano Reggiano. Serve the pasta still warm.