A 1.5kg chicken will yield approximately 1kg chicken meat when boned out. If you have the skills, the time and a sharp knife then by all means go ahead and do it yourself, otherwise ask your butcher.
Make sure your kitchen twine is cotton, not any type of plastic as you need it to be oven proof and food safe. When trussing your chicken, forgive yourself the odd, lumpen shape it may take on. Relax, this is home cooking not a restaurant with paying customers. It will taste just as delicious regardless of its contours.
Separate the sausage meat from their skins and discard the skin. Combine the fresh herbs and dried spices together with the sausage meat until well mixed.
Lay the boned-out chicken skin side down on your bench and pile the sausage mix into the centre in one thick log. As best you can, wrap the chicken meat over and around the sausage mix. With lengths of cotton kitchen twine approx 50cm long, firmly but not overly tightly tie the chicken around its girth every 5cm or so.
When ready to roast, lightly coat in some olive oil and sprinkle with a little salt. At 180 degrees Celsius, it should take around 60 minutes to cook. If you prefer to use a probe thermometer to confirm doneness, you’re looking for an internal temperature of 63 degrees Celsius. I tend to be a ‘pierce the flesh and if the juices run clear it’s cooked’ kind of person.
Allow the roast to sit uncovered for 5 minutes or so to rest, while you finish preparing the dinner. Use a sharp knife to carve slices, removing the twine as you go.