1. Prepare the Oven

Preheat the oven to 325°F (160°C).

Line an 8×8-inch square pan with parchment paper, allowing it to extend above the edges for easy removal.

Lightly grease the parchment.

2. Prepare the Honey Mixture

Mix together

• honey
• warm water

until completely smooth.

3. Beat the Egg Yolks

Whisk together

• egg yolks
• sugar
• honey mixture

for 3–5 minutes until pale, thick and ribbon-like.

4. Whip the Egg Whites

Beat the egg whites with salt until stiff glossy peaks form.

Avoid overbeating.

5. Fold Carefully

Fold one-third of the egg whites into the yolk mixture.

Sift in half of the bread flour.

Repeat with the remaining whites and flour.

Fold gently using a spatula.

Do not stir.

6. Remove Air Bubbles

Pour the batter into the prepared pan.

Tap the pan firmly on the counter 3–4 times.

Run a skewer through the batter to eliminate large air pockets.

7. Bake

Bake for 40–45 minutes until

• golden brown
• springy
• toothpick comes out clean

Avoid opening the oven during the first 35 minutes.

8. Cool

Cool inside the pan for 15 minutes.

Lift out using the parchment.

Cool completely on a rack.

9. Traditional Japanese Method

Wrap the slightly warm cake tightly in plastic wrap.

Allow it to rest overnight.

This creates the signature moist Castella texture.