Pick the basil leaves off the stems then rinse and pat the basil dry.
Place the basil, Parmesan cheese, pine nuts, garlic and lemon juice in a blender or food processor fitted with a blade attachment and blend.
Stop the blender or food processor and stir occasionally, scraping down the sides, to make sure all ingredients are combined. Add olive oil and pulse once more. The mixture should still be slightly chunky.
Season to taste with salt and pepper.
Bring a large pot of water to the boil; add the salt and bring back to the boil. Pour in the pasta and cook, stirring occasionally, until al dente, about 10 minutes.
Drain, reserving 1/2 cup of the pasta cooking water. Return the pasta to the pot. Ladle in the desired amount of pesto to coat the pasta, adding pasta water as needed to loosen the sauce. Stir and serve.