Prepare all ingredients. Take out milk, eggs, and butter 30 minutes before use.

Sift the pancake mix through a sieve.

Crack 2 eggs into a bowl and lightly whisk them.

Add sugar and milk to the eggs and mix until the sugar dissolves.

Combine the sifted pancake mix with the egg mixture, melted butter, and vanilla essence. Mix well.

Grease the rice cooker thoroughly with butter, pour in the batter, and tap the bottom to remove air bubbles.

Set the rice cooker to the 'multi-steam' function (35-40 minutes) and press the cook button.

Check if the castella is cooked by inserting a wooden skewer into the center. If it comes out clean, it's done.