Bring a large pot of salted water to a boil and cook the pasta according to package directions until al dente.
While the pasta cooks, prepare the sauce by mixing ricotta, Parmesan, olive oil, grated garlic, lemon zest, and lemon juice in a medium bowl.
Season with salt and black pepper, then stir until smooth and creamy.
Taste the sauce and adjust the seasoning if needed.
During the final minute of cooking, reserve ½ cup of the pasta cooking water.
Add the spinach to the boiling pasta and cook for 1 minute until wilted.
Drain the pasta and spinach, then return them to the pot.
Add the ricotta mixture along with a splash of the reserved pasta water.
Toss everything together until the Lemon Ricotta Pasta is creamy and evenly coated, adding more reserved water as needed.
Serve immediately with extra Parmesan, a drizzle of olive oil, lemon wedges, and optional red pepper flakes.