Cook the pasta al dente in salted water. When the pasta is done, add the peas and edamame and cook for 30 more seconds. Drain and reserve 1⁄2 cup of the pasta liquid. Place pasta and liquid in a bowl and add Parmesan, lemon juice, and some pepper. Toss well. Stir in pine nuts and watercress. Serve in bowls or plates with more Parmesan and a sprinkle of lemon zest.