In a large bowl, combine the ground beef, bread crumbs, milk, chopped onion, egg, garlic powder, salt, and pepper. Mix gently until all ingredients are well incorporated. Form the mixture into small meatballs, about 1-inch in diameter.
In your slow cooker, whisk together the cream of mushroom soup, beef broth, sour cream, and Worcestershire sauce until smooth and creamy.
Carefully place the meatballs into the slow cooker, making sure they are evenly coated in the sauce.
Cover the slow cooker and cook on low for 4-6 hours, or until the meatballs are cooked through and tender.
Once done, serve the Swedish meatballs hot over egg noodles or mashed potatoes.