Place the basil leaves, garlic, grated pecorino and pine nuts into a blender and process, gradually adding the olive oil until the mixture reaches the desired consistency. Season with salt and freshly ground black pepper.
Cook the fresh penne according to the packet instructions and drain, leaving a little of the cooking liquid in the bottom of the pan. Add the green pesto to the hot pasta and stir to coat.
To serve, spoon into a serving dish and scatter with grated pecorino.