Bring a large pot of water to a rolling boil, adding a pinch of salt. Drop in the fusilli and cook until al dente, about 8-10 minutes, until the noodles are slightly firm to the bite and fragrant.
Drain the pasta in a colander, then rinse thoroughly under cold water to stop the cooking process and cool the noodles down. Shake off excess water and transfer the pasta to a large mixing bowl.
While the pasta cools, chop the fresh basil and garlic into rough pieces, releasing their bright, green, and pungent aromas.
Add the chopped basil and garlic to the bowl with the cooled pasta. Pour in the pesto, olive oil, and lemon juice.
Using a spoon or spatula, toss everything together vigorously, coating each strand of pasta with the vibrant green pesto. The mixture will feel sticky and oily, spreading evenly as you stir.
Sprinkle the freshly grated Parmesan over the pasta and give it another gentle toss, ensuring the cheese is evenly distributed and the flavors meld.
Serve the pasta salad chilled, enjoying the crunch of cold noodles coated in bright, herby pesto with a sprinkle of extra Parmesan if desired.
