1: Clean the chestnuts. 2: Use a sharp knife to make a cut on the chestnut, being careful not to cut your hands. 3: Put the processed chestnuts into a casserole and add rock sugar. 4: Cover the chestnuts with water and bring to a boil over high heat. 5: After boiling, turn to low heat and simmer for 20 to 30 minutes, depending on the size of the chestnuts. 6: Li Zi spoke. 7: Place the chestnuts on a plate and serve.