Chicken and vegetables: Add onions, chicken mince, carrot and celery to the slow cooker insert.
Season: next add the chopped garlic, salt, black pepper and Italian herbs.
Liquids: pour in the passata, diced tomatoes, tomato paste and Worcestershire sauce and use a wooden spoon to stir till everything is combined.
Bay leaves: place the 2 dried bay leaves into the centre of the slow cooker.
Cook: put the lid on and cook the pasta sauce for 4 hours on high or 8 hours on low. Once the time is up remove the lid and use tongs to pick out and discard the bay leaves.
Spaghetti: read and follow the packet instructions to cook the spaghetti in a medium saucepan of boiling salted water. Moments before it is al dente, use a heatproof jug to scoop out and reserve 1-2 cups of the pasta water. Then use a colander to drain the pasta and discard the rest of the water.
Combine: add the drained hot pasta to the slow cooker then measure and add in ½ cup of the reserved pasta water. Use a pair of tongs to toss and combine.
To serve: grate some fresh parmesan cheese over the top, then sprinkle in some black pepper and add some basil leaves. Portion into bowls and provide forks and spoons for serving.