Preheat your oven to 325°F (160°C).

Line the baking pan with parchment paper, ensuring it covers the sides of the pan.

In a large bowl, beat the egg yolks with half of the sugar (100g) until the mixture is thick and pale.

Add the honey-water mixture and vanilla extract to the yolks, and mix well.

In a separate bowl, use an electric mixer to beat the egg whites until foamy.

Gradually add the remaining sugar (100g) while continuously beating until soft peaks form. This creates the meringue.

Gently fold one-third of the meringue into the egg yolk mixture using a spatula. Repeat with the remaining meringue in two more additions. Be careful not to deflate the meringue.

Sift the flour over the batter in two batches, folding gently after each addition until just combined.

Pour the batter into the prepared pan and smooth the top.

Tap the pan lightly on the counter to release any large air bubbles.

Place the pan in a larger baking tray and fill the tray with hot water (about an inch deep) to create a water bath.

Bake in the preheated oven for about 50-60 minutes, or until the cake is golden brown and a skewer inserted into the center comes out clean.

Remove the cake from the oven and drop the pan from a height of about 3 inches onto the counter to prevent shrinking.

Let the cake cool in the pan for about 10 minutes, then gently remove it from the pan and peel off the parchment paper.

Allow the cake to cool completely on a wire rack.

Once cooled, slice the cake into desired sizes.

Castella Cake is best enjoyed the day it's made but can be stored in an airtight container for up to 2 days.

Ensure all ingredients are at room temperature before starting.

Be gentle when folding the meringue into the batter to maintain its airy texture.

The water bath helps to cook the cake evenly and keep it moist.