1. Crack eggs into a bowl and add sugar. Whisk the eggs with a whisk to a foamy consistency (takes 20 minutes).

2. Add the flour, custard powder, baking powder and water, and mix again with a whisk until foamy (it takes 5 minutes).

3. Spread the butter, softened at room temperature, evenly all over the inner lining of the rice cooker.

4. Place the liner in the rice cooker and heat the pot on empty for 2 minutes. Pour the beaten egg batter into the liner.

5. Cover the top lid and press the cake button. 40 minutes later, the rice cooker will automatically enter the keep warm state.

6. Don't open the lid when the heating is finished, keep warm for 10 minutes before opening the lid. Use insulated gloves or rags to pad your hands to take out the inner liner of the rice cooker, and you can serve it while it's still hot.