In a large mixing bowl, combine the ground beef, grated onion, 1 clove of minced garlic, chopped parsley, egg, cumin, cinnamon, salt, and black pepper. Mix gently with your hands until just combined, being careful not to overwork the meat.

Form the mixture into golf-ball-sized meatballs, yielding about 16 to 18 portions. Place them on a plate and let them rest in the refrigerator for 10 minutes to help them hold their shape during cooking.

Heat the olive oil in a large, deep skillet or braising pan over medium-high heat. Add the meatballs in a single layer and sear until beautifully browned on all sides, about 5 to 7 minutes. Remove the meatballs to a clean plate and leave the drippings in the pan.

Lower the heat to medium and add the remaining 2 cloves of minced garlic to the skillet. Sauté until fragrant, about 30 seconds, ensuring the garlic does not burn.

Pour the crushed tomatoes and beef broth into the skillet, stirring to scrape up any browned savory bits from the bottom of the pan. Bring the sauce to a gentle simmer.

Return the browned meatballs to the skillet, nestling them gently into the tomato sauce. Cover the pan, reduce the heat to low, and let simmer for 20 to 25 minutes, or until the meatballs are cooked through and tender.

Remove the skillet from the heat and garnish with extra chopped parsley. Serve immediately warm alongside crusty bread, rice, or couscous to soak up the rich tomato sauce.