To butterfly your chicken, pat dry with a paper towel and place onto a solid chopping board breast side down.
Using a pair of kitchen scissors cut down either side of the back bone to remove in one piece. Turn the bird over and firmly press down on the breast to flatten the bird.
In a mortar and pestle add the peeled garlic cloves, red chilli, rosemary, salt and pepper and pound into a paste, zest the skin of the lemon and add to the paste then squeeze in the juice as well, add the olive oil and give it a good stir.
In a roasting pan place your butterflied chicken in and pour over the marinade, rubbing into the chicken on both sides. Allow this to marinade for minimum 2 hours, the longer the better.
When you are happy with the time you have given your chicken to marinate have your oven pre heated to 190 deg C. Place your chicken in skin side up and roast for 45 minutes. Once done allow to rest for 20 minutes before portioning.
To portion your chicken cut between the breast and leg to remove the legs, then cut the legs into the drum and thigh. Cut down the center of the breast and the cut each breast into 3-4 pieces. Use a heavy knife as you will cut through the bones.