Requires: kitchen string, tooth picks
Place the turkey breast between 2 sheets of plastic wrap or greaseproof paper and pound with a meat mallet or rolling pin until the turkey is approximately 1.5cm thick throughout. Peel off the plastic wrap or greaseproof paper and season lightly with salt and pepper.
Heat olive oil in a non-stick frying pan over medium heat. Add red onion and cook, stirring, until the onion is soft (approximately 4 minutes). Transfer to a medium-sized bowl and set aside to cool.
Place the bread slices in a small bowl and pour the milk over to soak for a few minutes. Break up the sausage meat with your hands and add it to the bowl with cooled onion. Add the milk soaked bread slices with any remaining milk into the bowl with the sausage mixture. Scatter the chopped sage leaves on top of the sausage mixture. Use clean hands (or you may wish to use disposable gloves) to mix until the sausage filling is well combined.
Arrange the pancetta slices on the plastic wrap or greaseproof paper, slightly overlapping. Place the turkey breast fillet on top of the pancetta slices. Spoon the sausage mixture evenly over the breast fillet leaving a 2cm border around the edges. Roll up the turkey breast fillet tightly to enclose the sausage filling. Place the whole sage leaves on top and use kitchen string to tie the turkey at 5cm intervals. Secure the ends with tooth picks.
Transfer the turkey to the baking tray. Cover with plastic wrap and refrigerate for a minimum of 1 hour before cooking.
Preheat the oven to 200°C conventional oven/ 180°C fan-forced (400° Fahrenheit/Gas 6). Line a baking tray with baking paper.
Remove the turkey breast from the fridge. Pour over the chicken stock and roast for 30 minutes. Pour the white wine over the turkey and baste with pan juices. Cook for a further 30 minutes or until cooked through.
Note: The turkey requires 40 minutes cooking time per kilogram.
Transfer turkey to a serving dish and set aside to rest for 10-15 minutes before serving – buon appetito.