Preheat the oven to 375°F. Spray a baking sheet with cooking spray and set aside.
Cook gnocchi according to package directions.
In a large bowl, add ground beef, garlic, egg, milk, breadcrumbs, parsley, salt, oregano, pepper, and Parmesan cheese. With clean hands, mix the ingredients until well combined. Form the meat mixture into 1-inch balls. Place the meatballs on the prepared baking sheet and cook for 18-20 minutes or until the meat is no longer pink.
Lower the oven temperature to 350°F.
Spray a 9x13-inch baking dish with cooking spray. Place the cooked meatballs and cooked gnocchi into the baking dish. Pour the jar of spaghetti sauce over the top. Stir the mixture with a spoon. Sprinkle Mozzarella cheese over the top.
Bake casserole for 30-35 minutes or until the cheese is melted and the sauce is bubbly.
To serve, garnish with chopped additional parsley if desired.
Notes
To make this recipe even quicker, use frozen, thawed meatballs. You will need about 24-30 of them.