Take the turkey out of the fridge 2 hours in advance.
Remove 12 nice cabbage leaves and cook them for 20 minutes in boiling water until tender. Dip them in cold water and dry them.
Lightly toast the fennel seeds in a frying pan without adding fat, and crush them with the back of a spoon.
Preheat the oven to 185°C. Place the minced meat in a large bowl. Add the finely chopped sage leaves and soft onion, along with the almonds, cranberries, pancetta, fennel seeds, pepper, and salt. Mix well and divide into 12 portions, forming small rolls. Place them in the cabbage leaves, tie them up, and add 0.5 sprig of rosemary. Brush them with butter and bake for 20 minutes in the oven. Set aside.
Cut the sweet potatoes (washed and unpeeled) into wedges. Spread them on a baking sheet lined with parchment paper, brush with olive oil, season with pepper and salt, and sprinkle with grated rosemary. Bake for 10 minutes in the oven at 185°C. Set aside.
Thoroughly grease a large baking dish with 30 g of butter. Spread the chopped celery over it, along with the onions cut into small wedges, the star anises, the unpeeled and halved cloves of garlic, the pears, and 2 mandarins (both unpeeled and cut into wedges), 4 sprigs of thyme, pepper, and salt. Generously butter the turkey and season it inside and out (with pepper and salt). Add 4 sprigs of thyme and 2 bay leaves between the legs. Cover with aluminum foil, but not hermetically. Bake for 3 hours at 180°C. After the first hour, regularly baste the turkey with the cooking juices.
Arrange the whole endive hearts in a large frying pan with the melted butter. Add the poultry stock, cover with a large circle of baking paper, and let simmer for about 20 minutes until tender. Remove the baking paper and let the juice reduce completely. Meanwhile, turn the endive hearts until they are golden brown all around. Season with pepper, salt, and nutmeg.
Remove the turkey from the oven and let the cabbage rolls and sweet potatoes cook further in the oven for 10 minutes.
Meanwhile, keep the turkey warm, covered with aluminum foil. Drain the fat and place the leftovers in a saucepan. Add poultry stock and cider and let it reduce slightly. Then strain this through a fine sieve into another pan. Bring to a boil, add the thickening agent, and season further.
Finish the turkey with grilled 0.5 mandarins and fresh bay leaves. Serve with the cabbage rolls, the sauce, the endive, and the sweet potatoes.
