1) Preheat oven to 190C/Gas 5.
2) Combine all ingredients, aside from the turkey, in a small mixing bowl.
3) Thoroughly rinse and dry the turkey well. Tuck the wings underneath the body and place the turkey in a roasting pan. Rub the butter mixture all over the turkey. Stuff, if desired.
4) Roast the turkey for 18 minutes per 500 g (including stuffing weight, if using). The turkey is done when an instant-read thermometer inserted into the thickest part of the thigh and deep into the stuffing registers 74C and the juices run clear. Remove from the oven and loosely tent with foil. Let rest for 20 minutes before carving.
5) To make the glaze, melt the butter in a skillet over medium heat. When the butter just begins to bubble, stir in the pecan halves. Let the pecan halves gently fry in the butter until they take on a lightly toasted color. Then add the sugar, treacle and honey, and stir until the sugar melts. Pour in the bourbon, raise the heat and bring to a boil. Lower the heat and simmer for 5 minutes until the glaze is smooth, except for the pecans, of course, and syrupy.
6) Let the glaze cool slightly and then pour it over the roasted turkey. Serve any extra glaze at the table.
Mix ingredients together and store in an airtight container for up to 6 months.