Bring a stockpot of water to a boil and salt it. Rinse the clams in cold water. Discard any that are open or damaged. Peel and finely chop the onion and garlic. Thinly slice the chili and parsley stalks then roughly chop the parsley leaves. Set aside.
Put the olive oil into the hot pan and add onion, chili and parsley stalks. Cook over low heat for about 3 minutes. Add the pasta to the boiling water and cook spaghetti according to package instructions.
Add garlic to the pan and continue to cook for about 1 minute. Now add the clams and shake the pan well, pour the wine into the pan and continue to cook. After about 3 minutes the clams will start to open but keep shaking the pan around until all of them have opened.
Drain the pasta, reserving 100 ml of pasta cooking water. Add pasta to the pan with clams and pour over the reserved pasta water. Cook over medium heat, tossing constantly, until pasta has soaked up some of the juices from the pan. Add the parsley, season to taste with black pepper.
Serve with white bread and a glass of delicious white wine. Bon appetite.