To make the meatballs, place the breadcrumbs in a small bowl and pour the milk over to soak for a few minutes. Place the wagyu (or other good quality beef) mince, egg, Parmigiano, mixed herbs and chopped basil into a medium sized bowl. Season well with sea salt.
Use clean hands (or you may wish to use disposable gloves) to mix the meatball mixture until just combined. Roll a heaped teaspoon size of meat mixture into a meatball using the palm of your hand. Transfer the meatball to a plate and repeat with the remaining meat mixture. Cover the meatballs with plastic wrap and refrigerate until ready to use.
To make the Italian tomato sauce, place the olive oil in a heavy-based stockpot over medium heat. Add the onion and cook for 3 minutes to soften. Add the Italian passata sauce, then fill the empty passata bottle with water. Add the water, sugar and sea salt to the stockpot. Bring to the boil, then reduce the heat to low and gently simmer for 25 minutes, stirring occasionally so that the sauce does not stick to the pot and burn.
Meanwhile to make the Besciamella (bechamel sauce), melt the butter in a medium-sized saucepan over medium heat until foaming. Add the flour and stir with a wooden spoon to form a smooth paste (a roux). Allow the flour and butter mixture to cook for a minute, continuously stirring (but do not allow it to brown). Remove the roux from the heat. Slowly pour the cold milk into the roux. Use a whisk to stir constantly until the mixture is smooth. Add the bay leaf and return milk to medium heat over the stovetop. Cook, continuing to whisk the milk until the Besciamella comes to the boil and thickens. Remove from heat. Season with salt to taste and stir in freshly grated nutmeg. Set aside to cool slightly.
Preheat the oven to 180°C conventional oven/ 160°C fan-forced (356° Fahrenheit/Gas 4).
Add the meatballs to the Italian tomato sauce and allow to cook for a further 25 minutes.
Meanwhile place a large pot with water on high heat and bring to the boil. Add a pinch of salt and Tortiglioni pasta to the boiling water and cook for 3/4 of the ‘al dente’ cooking time, referring to the cooking time specified in pasta packet instructions. Drain the pasta, then add to the stockpot with Italian tomato sauce. Toss to combine.
Ladle 1/2 of the saucy pasta with meatballs using the back of a ladle to press it down and level it. Spread 1/2 of the Besciamella over the pasta. Add a layer using 1/2 of the mozzarella cheese. Add the remaining saucy pasta with meatballs, once again pressing it down with a ladle. Set aside 50g mozzarella and add the remaining mozzarella cheese to top the pasta. Spread the remaining Besciamella on top of the pasta bake and smooth it.
Bake for 20 minutes. Remove the pasta bake from the oven and evenly spread the remaining 50g mozzarella. Bake for a further 5 minutes.
Cut the Wagyu meatball pasta bake into 6 portions and serve – buon appetito!