In a large bowl, add ground beef and all ingredients (except marinara sauce). Combine all ingredients until the meat mixture has all ingredients evenly distributed.
Heat broiler to high. Move rack to 4 or 5 inches from broiler. Cover baking sheet with foil, and spray with cooking spray.
Using your hands, shape the meat into about 1 to 2-inch sized meatballs, and place onto foil-covered baking sheet.
Broil meatballs for 3 to 4 minutes. Then turn them and broil for about another 3 minutes, until browned.
Spray a slow cooker with cooking spray. Place meatballs in the bottom of a slow cooker. Spoon marinara sauce over the top of the meatballs.
Cover and cook on low for about 4 hours.
Serve meatballs hot on top of pasta, or on a submarine sandwich, or by itself as an appetizer.