Preheat the broiler and position the rack about 8 inches below the heat.
Score the fat side of the pork belly 1/4-inch deep in a cross-hatch pattern and season liberally with salt and pepper on both sides. Place on a foiled lined broiler pan and broil, fat side up until golden brown, about 10 to 12 minutes. Turn over and broil for an additional 8 to 10 minutes. Remove from the oven and reduce the temperature to 300°F.
Heat the cider and 1 cup of the chicken broth to boiling in a dutch oven. Remove from the heat and add the cinnamon, allspice, cloves, carrots, celery, onion and garlic. Stir to combine and add the pork belly, fat side up. Add enough additional chicken broth to bring the liquid level just below the top of the pork belly.
Cover and bake for 3-1/2 hours, removing to baste the top of the meat every hour. After 3-1/2 hours, uncover and continue cooking for 1 more hour.
While the pork belly is braising for the last hour, bring the cider, sugar, cinnamon and ginger to a boil in a saucepan. Reduce the heat and simmer until the liquid has reduced and thickened to a syrupy consistency, about 20 minutes. Remove from the heat and set aside.
Remove the pork belly from the oven, discard the aromatics and braising liquid and slice the meat into 1-1/2 inch wide pieces. Heat the cider glaze over medium heat and add the pork belly, two pieces at a time, turning with tongs to coat thoroughly with the glaze.
To serve, plate a portion of cauliflower purée (see notes), top with a spoonful of caramelized onions and a piece of pork belly. Garnish with roasted carrots (see notes) and some chopped parsley.
Tips for Making This Recipe
How to Make the Cauliflower Puree
Steam or roast two 1-1/2 to 2-pound heads of cauliflower until very tender when pierced with a knife (you can also use two 16-ounce bags frozen).Transfer the florets to a large bowl and add 3 tablespoons of butter and 2 tablespoons of cream. Purée with an electric hand blender until smooth and silky (you can also use a food processor or blender). Season to taste with salt and pepper.
How to Make the Roasted Carrots
Preheat the oven to 400°F. Peel 6 carrots, cut them into 1-inch pieces, and toss them with a little olive oil, salt, and pepper.Spread the carrots in a single layer on a baking sheet and roast until tender, about 25 to 30 minutes.