Bring a large pot of salted water to a boil. Cook rigatoni until al dente. Reserve ½ cup pasta water, then drain the pasta.
In a blender or food processor, combine basil, parsley, lemon juice, lemon zest, garlic, Parmesan, red pepper flakes, olive oil, and a pinch of salt. Blend until smooth.
Toss the cooked rigatoni with the pesto, adding reserved pasta water as needed to achieve desired consistency.
Grate the hard-boiled eggs over the pasta using a fine grater or microplane.
Serve immediately, garnished with additional Parmesan and red pepper flakes, if desired. Enjoy!