Finely chop the washed and dried spinach, and mince the onion. In a bowl, combine the ground beef with the spinach, onion, egg, grated cheese, salt, and pepper. Mix everything together until well combined.

Prepare a small plate with breadcrumbs. Shape the mixture into meatballs, then roll each one in the breadcrumbs to coat them evenly. As you finish, place them in the basket of the air fryer.

Lightly brush the meatballs with extra virgin olive oil and cook for about 15 minutes. For the first 10 minutes, set the temperature to 356°F (180°C), then increase to 392°F (200°C) until fully cooked. Actual cooking time will depend on the size of the meatballs and your air fryer’s performance.

Alternatively, you can fry them in the traditional way or cook them in a pan for 15–20 minutes. First, brown them with a little olive oil and a clove of garlic, then add some water to finish cooking. This method will give you soft, juicy meatballs with a delicious sauce.