Bring a large pot of salted water to a boil. Cook the pasta according to package directions until al dente.
While the pasta cooks, combine the ricotta, pesto, parmesan cheese, and lemon zest in a large bowl.
Reserve one cup of pasta water, drain it once it is al dente, and return it to the pot. Add the ricotta pesto and cheese mixture and stir to combine.
If the sauce is too thick, add a ¼th cup of the reserved pasta water at a time and stir to combine until you reach your desired consistency. Garnish with more parmesan cheese and serve immediately.