In a large saucepan, sauté the onion in the olive oil until translucent. Add the peas and cook until tender, careful not to overcook them. Set aside ¼ of the peas for garnish.
In a large serving bowl, add a teaspoon of each salt and pepper to the ricotta. With a wooden spoon, mix together vigorously for a few minutes until the ricotta becomes creamy. Set aside.
Meanwhile, bring a pot of salted water to boil for the pasta. Cook the pasta until al dente. Drain the pasta, retaining a cup of the pasta cooking water.
Add the pasta to sauté pan with the peas, and heat together for about a minute. Then mix the pasta and peas into the bowl with the ricotta. If the pasta seems dry, add a bit of the retained cooking water. Serve immediately, garnished with the remaining peas and a sprinkle of pepper.