In a large bowl combine ground meat, breadcrumbs, Parmesan, egg, minced garlic, chopped onion, parsley, salt, pepper and Italian seasoning; mix gently until just combined.

Shape the mixture into even meatballs about 1 1/4–1 1/2 inches in diameter to ensure uniform cooking.

Optional: Heat oil in a skillet and brown meatballs quickly on all sides for better color and flavor; transfer to paper towel.

Pour marinara sauce into the crockpot; stir in brown sugar, ketchup and Worcestershire if using for a glossy glaze.

Arrange meatballs in a single layer in the sauce; try not to overcrowd — stack gently if needed.

Cover the crockpot and cook on low for 6–8 hours or on high for 3–4 hours until meatballs are cooked through and tender.

Stir gently halfway through cooking to coat meatballs and prevent sticking; spoon sauce over them.

Near the end of cooking, taste sauce and adjust seasoning with salt, pepper or a splash of vinegar for brightness.

If sauce is too thin, remove lid and cook on high for 15–30 minutes to thicken; alternatively stir in a cornstarch slurry to reach desired consistency.

Serve hot with pasta, rice, sub rolls or as appetizers; garnish with extra Parmesan and chopped parsley.