1. Bring a large pot of water with 1 tbsp. salt to a boil. Add pasta and boil until tender, 7 to 9 minutes.
2. Meanwhile, whirl garlic and parsley in a food processor until finely chopped. Add 1 1/2 cups peas, the ricotta, lemon juice and zest, 4 tbsp. oil, remaining 2 tsp. salt, and the pepper. Pulse to a coarse purée.
3. Reserve 1 cup pasta cooking water. Drain pasta and return to pot. Immediately add ricotta-pea purée and remaining 1 cup peas and stir until well mixed. Add a little pasta cooking water, if necessary, to loosen sauce.
4. Divide among 4 bowls. Sprinkle each with pine nuts and parmigiano, and drizzle with remaining 1 tbsp. oil.