Return the eggs to room temperature, then combine the butter and milk and dissolve in the microwave or a hot water bath. Coat the mold in butter, sprinkle with flour, and let chill in the fridge.
Start heating the oven up to 170°C. Crack the eggs into a bowl and whisk, then add in the sugar and start stirring immediately. Stir while placing in a hot water bath and warm up to body temperature.
Remove from the hot water bath, and whip with a hand mixer at high speed (for about 3 minutes). Whip until it turns white and thickens, then reduce to a medium speed and continue whipping (for about 3 minutes).
Scoop up some batter and draw a curl with it as it falls, and it is ready if it slowly disappears. Reduce to a low speed and adjust the consistency while slowly stirring.
Add in the sifted cake flour, and stir by scooping up from the bottom using a rubber spatula while rotating the bowl. Stir well.
Add in one scoop of the dissolved warm butter to the batter and mix well, disperse into Step 5, and mix quickly so that there are no inconsistencies. Scoop it up from the bottom.
Pour into the prepared mold drop to remove the air, and bake in an oven preheated to 170°C for 30~35 minutes.
Stick it with a toothpick, and it's done if it comes out clean. Drop it to remove the air, flip it upside down on a cake rack, and let cool.
Place into a plastic bag after it has cooled to prevent it from drying out.
Please place the butter into the hot water bath that you used for the eggs in order to keep it warm.
Story Behind this Recipe
I failed several times, but it finally took shape. This is a recipe that turns out nice and fluffy.
If you coat the mold with lots of butter, then you will be able to remove it cleanly from the mold, so I recommend using a lot. After sprinkling with flour, please thoroughly shake out the excess. After mixing the eggs into the flour, please stir sufficiently. Do it thoroughly and properly. If it's well-whipped the air bubbles will not pop.