In a small bowl, combine the breadcrumbs and milk. Let it soak for a minute until softened. In a large bowl, add the ground meat, soaked breadcrumbs, onion, egg, salt, pepper, and nutmeg. Mix until just combined.
Roll the mixture into small, bite-sized meatballs. Heat butter or oil in a large skillet over medium heat. Add the meatballs in batches and cook, turning often, until browned on all sides and cooked through. Remove from the skillet and set aside.
In the same skillet, melt the butter and whisk in the flour. Cook for about a minute, then slowly whisk in the beef broth, scraping up any browned bits from the pan. Let the gravy simmer until slightly thickened, then stir in the cream. Season with salt and pepper.
Return the meatballs to the skillet and gently simmer in the gravy for 5–10 minutes, allowing the flavors to come together.