Cook pasta according to package instructions until al dente, reserving 1 cup of cooking water. Drain pasta and set aside.
Make the sauce in the same pot: add the ricotta, parmesan, lemon zest and juice, salt and pepper to taste and stir until well combined.
Stir or whisk in ½ cup of pasta water until smooth.
Add the pasta and stir vigorously until the noodles are well coated adding more pasta water to loosen up the sauce as needed for a smooth sauce.
Stir in the arugula.
Serve immediately and top with remaining sauce from pan and a drizzle of olive oil. Serve with extra parmesan, red-pepper flakes and torn basil, if using and extra lemon wedges on the side.