Requires: kitchen string
Preheat the oven to 200°C conventional oven/ 180°C fan-forced (400° Fahrenheit/Gas 6). Line a baking tray with baking paper.
Cut the red onion in half. Finely chop ½ of the red onion. Set aside the remaining half. Heat half of the olive oil in a non-stick frying pan over medium heat. Add the finely chopped red onion and cook, stirring, until the onion is soft (approximately 4 minutes). Transfer to a small bowl and set aside to cool.
Use a julienne slicer or mandolin to cut the zucchini into thin strips. Alternatively, you can also use a sharp knife. Cut the julienne zucchini so that the thin strips are approximately 4cm long. Heat the remaining olive oil in the frying pan over medium heat. Add the zucchini and season with salt. Cook for 6-8 minutes or until lightly browned. Remove from the heat and set aside to cool.
To make the meat filling, place the bread slices in a small bowl and pour the milk over to soak for a few minutes. Add the pork and veal mince, sage and cooled red onion. Season with salt and pepper to taste and use clean hands (or you may wish to use disposable gloves) to mix the meat filling until well combined.
Roughly chop the remaining red onion, carrot and celery and transfer to the prepared baking tray. Add the bay leaves.
To make the rolled chicken roast, line a clean work surface with cling film (plastic wrap). Line 6 kitchen strings along the plastic wrap (each string approximately 30cm long). Arrange the pancetta in overlapping slices on top of the plastic wrap (and kitchen strings). Arrange the chicken fillet slices on top of the pancetta, overlapping slightly. Lightly season the chicken with salt and pepper. Spoon the meat filling evenly over the chicken, leaving a 2cm border around the edges. Place the cooked zucchini evenly over the meat filling and top with an even layer of mozzarella slices. Use the plastic wrap to roll up the chicken tightly to enclose the filling. Use kitchen string to tie the chicken at 5cm intervals. Secure the ends with toothpicks.
Transfer the rolled chicken roast to the prepared baking tray, seam side up, on top of the vegetables. Pour over the hot chicken stock. Roast for 20 minutes, then remove from the oven.
Turn the rolled chicken roast, pour the white wine over the chicken and baste with pan juices. Cook, for a further 20 minutes or until cooked through. Transfer chicken to a serving dish and set aside to rest for 5-10 minutes.
Meanwhile to make a gravy, place the pan juices into a small saucepan over medium heat. Reduce the cooking liquid until it has reduced by half. Strain the gravy through a sieve into a gravy boat, using the back of the ladle to extract as much flavour as possible.
Serve Rolled chicken roast with gravy and Italian roasted potatoes – buon appetito.