1. Prepare all ingredients, yam is steamed in advance, peeled and cut into small pieces
2. Take a pot and add appropriate water and sugar and cook until it melts
3. Add yam block
4. Press the yam with a spoon while cooking
5. When there are basically no large yam pieces, use a whisk to continue to boil the yam puree while mixing at high speed until it becomes smooth and thick.
6. Add milk and isinglass powder
7. Continue to cook and mix with a whisk until the isinglass powder is completely melted, and the yam paste is dense and somewhat textured (the texture is similar to cake batter, but not as obvious as the latter)
8. Pour the yam puree into the cake mold, let it cool and put it in the refrigerator
9. Take the frozen yam cake out of the mold (just like frozen cheese, use a hair dryer to blow on the periphery of the mold to release the mold)
10. Sprinkle matcha powder through a sieve on the surface of the yam cake and then cut it into pieces.