Bring a large pot of salted water to a boil. Cook pasta until al dente. Drain pasta, reserving 1 cup of pasta cooking liquid, and transfer to a large bowl.
Toss pasta with pesto until evenly coated. If the pasta looks a bit dry, splash in some pasta cooking liquid. Season to taste with salt.
At this point you can mix in other ingredients like halved cherry tomatoes and toasted pine nuts.
To serve, divide pasta between 4 plates and top with grated parmesan cheese and a freshly ground black pepper.