Baby Castella

Sift cake flour and baking powder together into a bowl. Set aside.

In a large mixing bowl, combine Eggs and Granulated sugar. Whisk vigorously until the mixture is pale yellow and thick, forming ribbons when lifted from the whisk. This technique is crucial for a light sponge, similar to wagashi dough handling.

Gently warm Honey, Mirin, and Koikuchi soy sauce in a small saucepan over low heat until just combined. Do not boil.