Steps

1. Separate 3 eggs into yolks and whites.
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2. Chill the separated egg whites in the refrigerator or freezer to make them easier to whip.
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3. In a bowl with the egg yolks, add 3 tbsp granulated sugar (half of the total), 3 tbsp vegetable oil, and 3 tbsp milk. Mix well.
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4. Add 70g hot cake mix and 10g cocoa powder to the mixed egg yolk mixture. Sift them in and mix until smooth.
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5. To the chilled egg whites, add the remaining 3 tbsp granulated sugar in 3-4 additions. Whip with a whisk until stiff peaks form to create meringue.
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6. Add 1/3 of the meringue to the bowl with the egg yolk mixture and mix until smooth.
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7. Add the egg yolk mixture to the bowl with the remaining meringue. Gently fold the mixtures together from the bottom, being careful not to deflate the meringue. This is the key to a fluffy texture.
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8. Lightly grease the inside of a 3-cup rice cooker.
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9. Pour the mixed batter into the rice cooker.
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10. Close the rice cooker lid and cook using the regular cooking mode.
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11. After cooking, check the doneness by inserting a bamboo skewer or toothpick.
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12. If it's undercooked, close the lid and cook for an additional 14 minutes (7 minutes twice). The cooking time may vary depending on your rice cooker, so continue cooking while checking with a skewer until no batter clings to it.
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13. Once cooked, remove the rice cooker pot and drop it on the counter a few times from a short height to release air bubbles.
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14. Place a wire rack over the pot, invert the rice cooker pot, and let it cool until it reaches room temperature.
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15. Once cooled, remove the cake from the pot, cut into desired pieces, and serve on a plate.
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16. Store any leftover cake by cutting it, wrapping it tightly in plastic wrap, or placing it in a bag and refrigerating. While delicious fresh, letting it sit in the refrigerator overnight will make the cake even more moist and flavorful. Ensure it's wrapped tightly to prevent drying out.
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