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add 4 egg yolk and ~7 teaspoon granulated sugar into stand mixer bowl with flat beater attachment
set stand mixer to low speed (stir-2) and let it run until the ingredients are smooth, creamy, and lighter in color
add ~1/2 cup 1/2 tablespoon coconut milk, 1/2 teaspoon soy sauce, and ~2 teaspoon ube extract into stand mixer bowl
set stand mixer to low speed (stir-2) and let it run until the ingredients are well-blended
sift 1 cup cake flour and 1 teaspoon baking powder into stand mixer bowl
set stand mixer to low speed (stir-2) and let it run until the ingredients are combined
add 4 egg white into large bowl
use a hand mixer until the ingredients are foamy
add 1/4 teaspoon cream of tartar into large bowl
use a hand mixer until the ingredients are whiter
gradually add ~1/2 cup powdered sugar while using the hand mixer until the ingredients form firm peaks
gradually add 1/2 meringue to yolk batter bowl and mix until incorporated
add yolk batter to meringue bowl
fold in with a spatula until batter has no white streaks remaining
oil up the rice cooker pot
pour batter into rice cooker pot
remove air bubbles from rice cooker pot
turn on rice cooker and set to "mixed"