2) For the meatballs, mix all ingredients very well in a stainless steel bowl. Hand roll the meatballs into 30g balls and place directly into the hot tomato sauce. Leave the sauce and meatballs to simmer for 2 hours. Remove the meatballs from the sauce and set aside.
3) To assemble the sandwich, combine the butter, garlic powder, chopped garlic, salt and pepper in a small saucepan. Heat until the butter is melted. Slice the bread lengthwise and remove any excess dough. Brush the butter mixture evenly all over both sides of the bread.
4) Alternate layers of spaghetti, sauce and meatballs throughout the bread. Top with basil leaves and Parmesan and close the sandwich.
5) Toast the sandwich for 3 minutes on each side on either a griddle or a panini press.
Slice the sandwich into suitable portions and serve.