Cut a deep incision in the side of the pork belly so that it can be stuffed and fill it with the ham, cheese, and prunes. Use toothpicks to secure the cut ends of the stuffed pork belly and use a razor to make a criss-cross pattern in the top surface of the meat. Season the top side of the stuffed pork belly with salt and season the bottom side of the stuffed pork belly with the BBQ seasoning. Place the seasoned, stuffed pork belly on a baking tray, transfer the baking tray to a preheated oven, and cook at 325°F for 2 to 2½ hours, until the core temperature of the meat has reached 175°F.
Rice the boiled potatoes over a large bowl and combine with the bacon, cheddar cheese, flour, egg yolks, potato starch, salt, and nutmeg. Pipe the mashed potato mixture into a clean Pringles can and freeze for 2 hours. After 2 hours, cut the end off of the Pringles can, push out the frozen mashed potato log, and cut it in half. Dredge each half in flour, egg whites, and bread crumbs. Heat some cooking oil in a large pot to 325°F and fry the giant croquettes for 12-15 minutes, until golden brown.
Melt the butter in a saucepan over medium heat and sauté the diced onion. Add the peas, heavy cream, and vegetable broth to the saucepan and let simmer for 5-10 minutes. Puree the pea mixture with an immersion blender until smooth and season with salt, pepper, and nutmeg. Serve the stuffed pork belly with the giant croquettes and homemade pea puree.