1. Heat oven to 325°F. Arrange cornbread in single layer on 2 large baking sheets; bake until just dry, about 20 minutes. Transfer cornbread from 1 pan to a large bowl; pour pecans onto empty pan and toast in oven until golden, 10 to 20 minutes. Once cornbread is cooled, empty second pan into bowl with first.
2. Cut leeks in half lengthwise and then cut crosswise into 1/2-inch pieces. Wash in bowl of cold water; place in colander to drain. In a 12-inch skillet, cook and stir leeks and celery in butter with salt and pepper to taste over medium-low heat until leeks are tender, about 25 minutes.
3. Crumble sausage and add to leek mixture; cook over medium heat, stirring occasionally, until sausage is browned and thoroughly cooked, about 5 minutes.
4. Cook and stir cranberries and sugar in small saucepan over medium-high heat for 5 minutes or until some begin to burst.
5. Add pecans, sausage mixture, cranberries, parsley and chicken stock to bowl with cornbread; toss to combine. Salt and pepper to taste. Cool stuffing completely.
6. Set rack of pork on cutting board, fat side up, with the bones facing you. Using a sharp knife with thin blade, run the blade between the bones and the meat, partially separating the meat from the bones leaving 1 1/2 inches of it attached at the bottom.
7. Slice through the middle of the pork meat, butterflying it by leaving about 1/2-inch uncut on the near where the bones attach.
8. Open up pocket in the meat and season well with salt and pepper. Pack 3/4 of the stuffing into the slit in the roast and roll it back into shape. Pack the remaining stuffing where meat was separated from the bones. Cut butcher's twine and tie the roast between the bones; place in large roasting pan, fat side up.
9. Heat oven to 400°F. Combine rosemary and olive oil with 1 tablespoon salt and 2 teaspoons pepper; spread paste over outside of meat. Roast pork in lower third of oven for 15 minutes.
10. Reduce oven temperature to 300°F. and continue roasting for 1 1/2 hours until internal temperature reaches 145°F. to 160°F.
11. Transfer roast to cutting board and let stand for 20 minutes. Remove strings and cut between bones into individual chops for serving.