Heat a large saucepan over low-medium heat and add the olive oil and onion. Fry the onion for about 6 minutes until fragrant and starting to brown. Increase the heat to medium-high and add the frozen peas.
Fry for about 2 minutes, then add the stock and bring to a simmer. Add the pasta and cook until the pasta is al dente. There should still be a very little bit of liquid around the pasta. Stir through the parmesan, season with black pepper, then serve. The finished dish should be the texture of risotto.
