Cook spaghetti in salted boiling water until al dente. Reserve ½ cup pasta water and drain.
Prepare pesto by blending fresh basil, Parmesan cheese, garlic, pine nuts, and olive oil until smooth.
Transfer the pesto to a large pan or bowl.
Add the hot spaghetti and toss until evenly coated.
Add a little reserved pasta water to create a smooth, glossy sauce.
Season with salt and black pepper to taste.
Serve immediately with extra Parmesan and fresh basil.