01 -
In a large bowl, gently combine ground beef, breadcrumbs, Parmesan, egg, chopped onion, garlic powder, salt, and black pepper using your hands until just mixed to avoid toughness.
02 -
Roll the mixture into meatballs approximately 2.5 to 3.8 centimeters in diameter. Rustic shapes are acceptable.
03 -
Place the meatballs snugly into the crockpot, layering if necessary as they will shrink while cooking.
04 -
In a separate bowl, whisk together beef broth and French onion soup mix until fully combined and pour over the meatballs ensuring they are submerged.
05 -
Cover and cook on low heat for 6 to 8 hours for optimal flavor development, or on high for 3 to 4 hours if pressed for time.
06 -
Approximately 15 minutes before serving, sprinkle shredded mozzarella evenly over meatballs, re-cover, and allow cheese to melt.