Bring a large pot of salted water to a boil.
If using store-bought pasta, add the pasta and cook according to the package directions until al dente.
If using homemade pasta, prepare the sourdough pasta according to the Easy Sourdough Pasta Recipe and cook for about 2 to 3 minutes, or until al dente.
Before draining the pasta, reserve about ½ cup of the pasta cooking water.
Drain the pasta and immediately transfer it to a large bowl or skillet.
Add ½ cup of the fresh basil pesto and toss until the pasta is evenly coated.
Add the reserved pasta water a tablespoon or two at a time, tossing between additions, until the pesto becomes silky and coats the noodles well.
Stir in the Parmesan cheese.
Taste and add additional pesto or salt as needed.
Serve immediately with additional Parmesan cheese over the top.