Put ingredients other than butter into a kneader and turn it into a kneading function. When it lumps together, add butter at room temperature and knead it.When the elastic dough is completed, it is rounded and put in a bowl, wrap it on the top, pierce the breathing holes in three to four places, and place it at room temperature for the first fermentation.Ferment the dough until it is more than doubled in volume.

Steam the sweet potatoes in a steamer, peel them, and sieve them when they are hot.Add caramel sauce, cinnamon powder, and salt and mix them evenly.

After fermentation, press the dough by hand to remove air bubbles, and push it with a rolling pin to make a square about 30*40cm.Leave a little bit of the edges here and put on the sweet potato cream.

Sprinkle the walnuts evenly and roll them tightly from the bottom.

Finish by pinching the ends, and cut the dough to a height of 3.5cm using silk thread.You can cut it with a knife, but it's easy to mess up.

Put the cut dough in a mold, cover the top with vinyl and let it ferment at room temperature for a second time.Ferment until the dough is nearly doubled. Place in a preheated oven at 185 and bake for 15 to 17 minutes.