1. Preheat the Oven:
- Preheat your oven to 325°F (163°C). Grease and line a rectangular or square cake pan with parchment paper.
2. Prepare the Egg Mixture:
- In a heatproof bowl, combine the eggs and sugar. Place the bowl over a pot of simmering water (double boiler) and whisk continuously until the sugar dissolves. The mixture should reach a temperature of about 110°F (43°C). This step helps create a stable and airy foam.
3. Whip the Eggs:
- Remove the bowl from the heat and use a stand mixer or handheld mixer to beat the egg mixture on high speed until it becomes thick, pale, and triples in volume. This may take about 8-10 minutes.
4. Add Dry Ingredients:
- Sift the cake flour over the whipped egg mixture in three batches, gently folding in each batch until just combined. Be careful not to deflate the airy texture.
5. Combine Wet Ingredients:
- In a separate bowl, mix together honey (or light corn syrup), mirin, water, and melted butter. Gently fold this mixture into the batter until fully incorporated.
6. Pour into the Pan:
- Pour the batter into the prepared cake pan. Tap the pan on the counter a few times to remove any air bubbles.
7. Bake:
- Bake in the preheated oven for about 45-50 minutes or until a toothpick inserted into the center comes out clean.
8. Cool and Slice:
- Allow the cake to cool in the pan for 10 minutes, then transfer it to a wire rack to cool completely.
9. Optional: Honey Glaze (Tsukimidoro):
- Heat a mixture of honey and water in a saucepan until it forms a glaze. Brush this glaze over the cooled cake for an extra layer of sweetness and shine.
10. Enjoy:
- Slice your Fluffy Castella Sponge Cake into squares or rectangles and savor the soft, cotton-like texture that melts in your mouth.
Conclusion:
The art of crafting a Fluffy Castella Sponge Cake is a delightful experience that brings a touch of Japanese elegance to your baking repertoire. With its cloud-like texture and subtle sweetness, this cake is a wonderful addition to tea time or any special occasion. Enjoy the process of creating this Japanese classic and savor the delicate flavors that make Castella Sponge Cake a beloved treat around the world.