Chop up the chocolate and put it in a paper bag or a small pot. Boil hot water in the cauldron, and control the temperature at 40~60 degrees. Put the small pot in the big pot, and you can melt the chocolate without adding water. After the chocolate is completely melted to no particles, it is cooled to 35 degrees, poured into the mold and filled. Let it stand at room temperature for about 10 minute, and turn the mold upside down to form the outer chocolate. Pour in sandwiches, jam, hazelnut sauce or chocolate of another color. Pour it for 8 minutes and let it stand for 10 minute. Then pour in the melted white chocolate, cover the mold, scrape it flat with a scraper, and put it in the refrigerator for 20 minutes. After taking out, gently tap the mold, and the completely solidified chocolate will be easily demoulded. A cut sandwich.