In a large bowl, mix the ground beef, bread crumbs, onion, egg, garlic, parsley, oregano, and salt and pepper with clean hands.
Shape the mixture into 2-inch balls.
Place the meatballs into a large skillet. Fry them until the sides are thoroughly browned and cooked (about 6-7 minutes per batch).
Transfer the browned meatballs to your crockpot. Add the crushed tomatoes and tomato paste.
Cook on low for 4-5 hours or on high for 2-3 hours.
After the allotted time, serve with Parmesan cheese if desired.