In a medium-sized mixing bowl, combine ricotta, olive oil, Parmesan, lemon juice and zest. Season with salt and pepper, stir in chili flakes and set aside.
In a large pot or Dutch oven, cook pasta according to package instructions to al dente. Reserve 1 cup pasta water, drain pasta and return to pot.
Add ricotta mixture, parsley and reserved pasta water to pasta and toss. Taste and add more salt, pepper or chili flakes as desired.
Transfer to serving bowls and top with more Parmesan and a drizzle of olive oil. Serve immediately.