Bring a large pot of well-salted water to a boil over high heat. Add the rigatoni, then cook until al dente (stirring often).
Reserve 1 cup pasta cooking water, then drain pasta well.
While pasta cooks, mince garlic and nuts in food processor.
Add basil, Parmesan, olive oil, salt, and lemon zest to nut mixture. Process until smooth. (Stop to scrape down side of bowl, as needed, to ensure everything is well combined.)
Mix in ricotta, blending until smooth. Taste, then season to taste with additional salt, if desired.
Return pasta to pot, along with pesto ricotta sauce and about ½ of the reserved cooking water. Mix well (adding additional water, if needed), until pasta is well-coated. Season with extra salt, if needed.
Serve pasta hot, topped with grated Parmesan cheese. Enjoy!
Notes
Swap out the rigatoni for other chunky pasta shapes, such as fusilli, penne, or farfalle. Strands of pasta (like spaghetti, linguine, or fettuccine) can also be used, although they won't hold the sauce quite as well.I recommend using whole milk ricotta for the creamiest results (although part-skim will also work).Make sure to read the info before this recipe card for helpful tips, recipe variations, serving suggestions, and more!