1. For the roast: Preheat oven to 425 degrees. Place vegetables on a rimmed baking sheet. Add 1 cup water.

2. Season pork all over with salt and pepper. Cover each exposed bone with foil to prevent it from burning. Place 2 to 3 cups stuffing loosely in center, forming a dome (do not pack). Cover stuffing loosely with parchment and then foil. Place pork on top of vegetables.

3. Roast for 20 minutes. Reduce oven to 350 degrees, and continue to cook, basting roast and stuffing every 30 minutes and adding about 1 cup water each time to prevent vegetables from burning. Roast is done when a meat thermometer inserted into thickest part of pork (without touching bone) registers 160 degrees, about 2 hours. Transfer roast to a plate, reserving pan juices and baking sheet and discarding the vegetables. Tent roast with foil, and let rest for at least 30 minutes.

4. For the gravy: Pour reserved pan juices into a glass measuring cup or a gravy separator, and let stand until separated, about 10 minutes. Pour off fat. Strain remaining pan juices (you should have 1/2 cup; add stock if needed).

5. Place reserved baking sheet over 2 burners on medium-high heat. Add Marsala, and stir with a wooden spoon to loosen browned bits. Strain into a saucepan, and stir in pan juices, stock, and demi-glace if using. Bring to a boil, and cook until reduced to 1 1/2 cups, about 5 minutes. Reduce heat to a gentle simmer, and season with salt and pepper. Stir together flour and butter until smooth, and gradually whisk into simmering gravy. Cook until gravy is slightly thick and glossy, 3 to 5 minutes.

6. Transfer stuffed roast to a serving platter. Stir any juices that have collected on plate into the gravy.

7. For the garnish: Melt butter in a skillet over medium-high heat. Add pears and kumquats, and cook until tender, about 9 minutes. Stir in honey, and cook until pears are golden, about 3 minutes.

8. Garnish roast with pears, kumquats, and leaves if using. Serve with gravy and remaining stuffing.