In a large bowl mix ground beef, bread crumbs, egg, parsley, garlic, 1/2 cup parmesan, salt and pepper.
Portion in to golf ball sized meatballs roughly 2 to 3 oz or 10 to 12 total for 10 servings
Heat a skillet over med high heat
Add olive oil
Sear meatballs until brown on both sides
Add marinara and heat to a simmer
Add remaining 1/4 cup parmesan and stir in to sauce
Simmer 10 min
Top each meatball with slices of mozzarella and cover until melted.
Toothpick each meatball
Remove to serving tray
Top with whole basil leaves