1. Prepare a basin of warm water at about 30 to 40 degrees Celsius, pour the chestnuts into the water and soak them for a period of time.

2. The chestnuts that have absorbed water will slowly sink to the bottom of the water, which is considered soaked.

3. Prepare a clean pressure cooker, pour the chestnuts into the pot, then add an appropriate amount of rock sugar and water to the pot and start cooking.

4. Cook for 30 minutes.