To make the meatballs: Place the bread slices in a small bowl and pour the milk over to soak for a few minutes. Place the beef mince, pork mince, egg, parsley, mixed herbs and fennel seeds into a medium sized bowl. Add the milk soaked bread slices with any remaining milk into the bowl with the mince mixture. Season well with salt and pepper.
Use clean hands (or you may wish to use disposable gloves) to break up the bread evenly and mix until just combined. Using wet hands, roll a tablespoon of meat mixture into a meatball using the palm of your hand. Transfer meatball to a plate and repeat with the remaining meat mixture. Cover the meatballs with plastic wrap and refrigerate for a minimum of 15 minutes before cooking.
To make the Italian tomato sauce: Place the olive oil in a heavy-based stockpot over medium heat. Add the onion and cook until soft. Add the Italian passata sauce and water. Bring to the boil, then reduce the heat to low and gently simmer.
Add the tomato paste and stir to combine. Then add the meatballs and allow to cook, stirring occasionally so that the sauce does not stick to the pot and burn, for approximately 1 hour or until the sauce has reduced to your required consistency then take off the heat.
To cook the pasta: Place a large pot with water on high heat and bring to the boil. Add a pinch of salt and spaghetti pasta to the boiling water and cook until ‘al dente’ – refer to the cooking time specified in pasta packet instructions. Drain the pasta.
Place the stockpot with Italian tomato sauce and meatballs back onto medium heat. Add pasta and toss to combine, then remove from the heat. Divide among deep serving bowls and serve with extra Italian tomato sauce and grated Parmigiano Reggiano on top – Buon appetito.