Bring a large pot of salted water to boil. Cook the tagliatelle to al dente and save ½ cup of pasta water.
Add basil, pine nuts, garlic, and salt to blender or food processor and blend until thoroughly combined.
With blender or food processor on, slowly add olive oil and lemon juice until well combined. Add the Parmesan and blend for 10 more seconds until just combined.
Add the cooked pasta to a mixing bowl. Add the pesto and ¼ cup of reserved pasta water, tossing to combine. Add more water if still too thick. Top with some Parmesan and fresh basil.
Notes
Opt for freshly grated Parmesan to enhance the sauce, avoiding pre-shredded options that may include wood pulp. Choosing blocks of Parmesan cheese is not only more cost-effective but ensures a purer product.
Use freshly squeezed lemon juice as it tastes better and is cheaper. No store-bought bottle.
Ensure that the water used for cooking the pasta is salted, as a portion of the flavor is derived from it.
Avoid heating your pesto, as doing so diminishes some of its aroma and flavor. Simply add it to the hot pasta.