Heat the oil in a saucepan. Fry the onion and peppers for 7 mins, then stir through the garlic and chilli flakes and cook for 1 min. Add the tomatoes, giant couscous and veg stock and bring to a simmer.
Season to taste, then add the meatballs and spinach. Simmer for 5-7 mins or until cooked through. Ladle into bowls and top with the basil and some parmesan, if you like.