Stir together ricotta, Parmesan and salt in a large bowl.
Bring a large pot of salted water to boil. Cook pasta until just al dente, 11 to 12 minutes (or as package label directs). Add edamame to pot for final 1 minute of pasta cooking time. Reserve 1 cup cooking water and drain pasta and edamame. Add pasta to bowl with cheese mixture along with 1/2 cup cooking water and stir. If mixture is too dry, add more water, 1 Tbsp. at a time, until creamy. Stir in mint, season with salt and pepper and serve immediately.