In a large mixing bowl, combine ground beef, egg, grated Parmesan cheese, chopped onion, parsley, salt, garlic powder, oregano, and black pepper.

Mix the ingredients with clean hands until well combined, but be careful not to overmix to avoid tough meatballs.

Form the mixture into 1 1/2-inch meatballs, rolling them between your palms to create a smooth surface.

Heat olive oil in a large skillet over medium heat. Once hot, add the meatballs in batches, making sure not to overcrowd the pan.

Cook the meatballs for about 10 minutes, turning occasionally, until they are browned on all sides and cooked through to an internal temperature of 160°F.

Remove the meatballs from the skillet and let them rest for a few minutes before serving with your favorite sauce or as part of a main dish.