Blitz up the fresh basil, garlic, walnuts, salt, lemon juice, and olive oil in a food processor.
If you can have dairy, add some parmesan cheese.
Before straining the pasta, scoop out a cup of the pasta water and set it aside.
Add the pesto to the pasta and the reserved pasta water, then stir until the pesto is evenly distributed.
Grate more cheese on top if desired.
