Bring a large pot of water to a boil and salt it. Cook the pasta.
About 2 minutes before the pasta is done, add the peas to the pot.
Reserve one cup pasta cooking water, then drain penne and peas.
Add them back to the empty pot (do not put back on the heat) with 1/2 cup pasta cooking water, some olive oil (I used about 2 Tablespoons), salt and freshly ground black pepper. Add the pasta to a serving bowl.
Spoon in the ricotta cheese and give it a good stir. If pasta seems a little dry, add a bit more of the pasta cooking water you reserved. Drizzle on the reserved tablespoon of olive oil. You should have a creamy ricotta sauce. Add a little more pasta water or olive oil if needed.
Stir in the fresh lemon zest and lemon juice. Check the salt and pepper and add more, if needed, to your taste.
When serving in the bowls, sprinkle on the pine nuts, Parmiggiano-Reggiano cheese, and parsley.