In a bowl, combine ground beef, chopped onion, egg, breadcrumbs, parsley, salt, and pepper.
Mix well until all ingredients are thoroughly combined.
Form the mixture into meatballs, approximately the size of a golf ball.
In a large pot, melt butter over medium heat.
Add the meatballs to the pot and brown them on all sides.
Once browned, remove the meatballs and set them aside.
Pour beef broth into the pot, scraping up any browned bits.
Return the meatballs to the pot and simmer for 20 minutes.
In a separate bowl, mix cream and capers.
After 20 minutes, add the cream mixture to the pot and cook for an additional 5 minutes.