If you have the opportunity to use fresh beans, shell the peas and cook the pods or even the stems in the vegetable stock over low flame first.
Use a larger pan, smelt half of the butter and add the oil. Add the small diced onions and the finely chopped parsley. Sauté onions for about 3-4 minutes until they are translucent.
Add the peas and a ladle of vegetable stock and cook over low flame for 5 minutes.
Pour the remaining stock into the peas and add the rice. Stir frequently until rice is al dente, which means it is cooked, tender, but firm to the bite.
Take your pan off the heat, add grated Parmesan cheese and the remaining butter, serve hot.