Castella Cake Recipe: History, Science of Meringue, and How to Make One at Home

I loved rainy days when I was an elementary kid as the Castella my mom made was waiting for me. The smell came first—warm, sweet, faintly caramelized— before I opened the gate. 

To me, Castella isn't just a sponge cake; it is the flavor of my mother’s love. Recently, yearning for that nostalgic sweetness, I checked a recipe and made it in my kitchen.

A Journey Across the Sea: The History of Castella

The story of Castella is one of cultural fusion. It originated from the Spanish region of Castile (hence the name Pão de Castela or "Bread of Castile") and was brought to Japan by Portuguese merchants in the 16th century.

What makes it unique is its evolution. While Western sponge cakes often rely on butter, the traditional Castella is fat-free, —made simply from eggs, sugar, and flour—, refined over centuries into the dense, moist, and springy delicacy we adore today in East Asia.

The Magic of Meringue

The secret to a perfect Castella—one that doesn't collapse but stands tall and proud—lies in the Meringue.

When you whisk egg whites, you are performing a culinary miracle. Egg whites are approximately 90% water and 10% protein. As you beat them, the proteins reorient themselves around pockets of air, forming a flexible film that traps gas within a network—transforming liquid into structure.

Sugar enters not for sweetness alone, but for diplomacy: it delays protein coagulation, stabilizes the foam, and lends elasticity, ensuring the bubbles don’t collapse before heat sets them in place. 

Historically, the technique of whipping egg whites dates back to at least the 17th century in European kitchens, where early meringues—meringues à la neige—were baked into crisp shells. But in castella, the meringue is not dried into brittleness, but folded gently into yolk-rich batter, and baked slowly until the foam becomes golden sponge cake.

The Recipe: Recreating the Childhood Memory

Inspired by the meticulous method found on Kkom-ji's Kitchen, here is how I made:

Ingredients:

• Large Eggs: 6 (at room temperature)

• Sugar: 90g 

• Milk: 70ml or Heavy cream 2TBSP with 50ml water (as I didn’t have milk, I used heavy cream)

• Rice Flour: 120g 

• Salt: ¾ tsp

• Vegetable oil: 45ml

The Method:

1. Separate your eggs. In a bowl, whisk egg yolks with salt, milk, oil, and rice flour.

2. Whisk the whites, gradually adding sugar until you achieve a dense, glossy meringue.

   
   
   

3. Fold the meringue into the yolk batter in three additions, careful not to deflate the foam.

4. Pour the batter into Pressure rice cooker (for 6 people) and bake for 45 minutes with its steaming function.