Steps

1. Get all of your ingredients and equipment ready. Fill and boil the kettle. Put a large frying pan on a high heat. Put the standard blade attachment into the food processor.
2. Trim the scallions, carrot, and celery. Roughly chop all the vegetables, then blitz in the food processor with the chiles (stalks removed). Add the sausages, 1 heaping teaspoon of fennel seeds, and 1 teaspoon of oregano. Keep pulsing until well mixed, then spoon this mixture into the hot frying pan with a lug of olive oil, breaking it up and stirring as you go. Keep checking on it and stirring while you get on with other jobs. Put a large deep saucepan on low heat and fill with boiled water. Fill and reboil the kettle.
3. Top up the saucepan with more boiled water if needed. Season well, then add the penne and cook following the package instructions, with the lid askew.
4. Crush 4 unpeeled garlic cloves into the sausage mixture and stir in ¼ cup of balsamic vinegar and the canned tomatoes. Add a little of the starchy cooking water from the pasta to loosen, if needed.
5. Drain the pasta, reserving about a wine-glass worth of cooking water. Tip the pasta into the pan of sauce and give it a gentle stir, adding enough of the cooking water to bring it to a silky consistency. Taste, correct the seasoning, then tip into a large serving bowl and take straight to the table with the rest of the Parmesan for grating over. Scatter over a few basil leaves.