Gently cook the onion and pancetta on a low heat in the olive oil for 3-4 minutes, stirring every so often.
Meanwhile cook the pasta in boiling salted water according to the packet's instructions, then drain into a colander.
Add the wild garlic leaves and butter to the pancetta and onion, season, then toss with the pasta and serve. You can stir a tablespoon of Parmesan into the pasta before serving if you wish.