Put on the water for the pasta, bring to the boil, add a pinch of salt and add the penne to the water.
In a heavy saucepan or pan, slowly heat the oil. Add the spring onions, the feta and half of the parmesan or grana padano. Mix everything together and cook for about 1 minute. Stir in tomatoes and basil and season with salt and pepper.
Take the sauce off the stove as soon as it gets warm and mix it with the finished hot penne.