Place beef, Parmesan, egg, salt and spices in a bowl and blend thoroughly. Form the mixture into meatballs, about 1 Oz (30 grams) each. It helps to keep your hands wet while forming the balls.
Heat up olive oil in a large pan and sauté the meatballs until they’re golden brown on all sides.
Lower the heat and add the canned tomatoes. Let simmer for 15 minutes, stirring every couple of minutes. Season to taste. Add parsley and stir. You can prepare the dish up to this point for freezing.
Melt the butter in a separate pan and fry spinach for 1-2 minutes, stirring continuously. Season to taste. Add spinach to meatballs, and stir to combine.
Serve with mozzarella on top, torn into bite-sized pieces.
