Mix the ricotta, 1/2 cup parmesan, and 1 tablespoon lemon zest in a small bowl. Season the mixture with salt and pepper.
Meanwhile, bring a medium pot of generously salted water to a boil. Add the pasta and cook according to package directions until al dente. Drain the pasta and reserve 1 cup of water.
Heat the butter in a skillet over medium heat. Drain the peas and cook 1-2 minutes. Add the pasta to the peas and cook for 1 minute.
Pour the pasta and peas into a large bowl. Mix in the ricotta mixture and 1/4 cup of pasta water.
Stir until the ricotta is evenly incorporated with the pasta. If it is too dry, add reserved water a little at a time. Add the remaining parmesan and remove from heat.
Add chopped mint and additional pepper.