Preheat the oven to 375 degrees F
To a large bowl combine the ground beef, onion, garlic, parsley, breadcrumbs, pecorino Romano, eggs, and salt & pepper.
Mix with your hands, but just until combined. Don't over mix!
Roll them into 1 & 1/2 inch meatballs and place into a greased casserole dish.
Top the meatballs with the jar of sauce (or homemade sauce)
Top with freshly shredded mozzarella cheese
garnish with cracked black pepper and fresh parlsey
Bake covered tightly at 375 degrees F. for 25 minutes.
Remove from the oven and uncover (remove the foil)
Put the meatball casserole back into the oven uncovered at the same temperature for another 15 minutes or until the cheese is melty and bubbly
Serve with pasta and enjoy!