Steps:
1. Mix all the materials needed for water-oil skin, knead into smooth dough, cover with plastic wrap and relax for 30 minutes.
2. Knead the flour and lard needed in the dough until smooth.
3. Beat the peeled and cooked chestnuts into fine particles with a rolling pin or a cooking machine, add sugar and lard and knead well for later use.
4. Divide the loose oil skin, crisp dough and stuffing into 10 parts. Flatten the oil skin into a circle, put the cake in the center of the oil skin, pinch it, turn it down into a circle, then cover it with plastic wrap and let it stand 15 minutes.
5. Roll the loosened dough into a long oval shape and roll it from top to bottom. Cover with plastic wrap and relax 15 minutes.
6. Roll the dough into an oval shape again, roll it up and let it stand 15 minutes.
7. Flatten the dough vertically into a circle, and roll it with a rolling pin into a round dough sheet with a thick middle and thin sides.
8. Wrap the stuffing tightly and press it down into a round cake.
9. Preheat the oven to 200 degrees. Put the bread in the baking tray, brush with egg liquid and sprinkle with white sesame seeds. Put it in the middle and lower layer of the oven and bake for 20 minutes.