Castella

Castella, or kasutera, is a light, sponge-like cake that became a staple of Japanese confectionery in Nagasaki. Traditionally made from simple ingredients—eggs, sugar, flour, and a syrup such as mizuame—the batter is whisked to a high volume and baked in a shallow loaf or rectangular mold, often in a water bath to maintain moisture and an even crumb. The result is a moist, finely textured cake with a delicate sweetness.

Historically, Castella was introduced to Japan in the 16th century by Portuguese merchants and missionaries during the Nanban trade. The dish was adapted by Japanese bakers and became associated with Nagasaki, which developed a distinctive tradition of Castella production. The name is thought to derive from the Portuguese “Castella” (Castile cake). Over time, its popularity spread to other parts of Japan and beyond, where it has remained a recognizable regional specialty and a common gift.

In terms of production and variation, traditional Castella relies on a short list of core ingredients, though modern versions experiment with flavors and textures. Some bakers use honey or brown sugar to alter the sweetness and color, while others incorporate matcha, chocolate, or kuromitsu for different profiles. Castella is typically sold in long rectangular loaves and sliced for serving; it often remains moist if kept properly but is also appreciated for developing a richer flavor as it ages.