Tokusen Gosan Castella is a Japanese sponge cake made by Bunmeidō, a confectionery house rooted in Nagasaki’s castella-making tradition. It is a premium offering based on the gosan-yaki method documented in historical Japanese sources.

It is made from eggs, sugar, mizuame starch syrup, honey, and wheat flour. The recipe’s defining feature is a 5:3 ratio of egg yolks to egg whites by weight, which contributes to its rich flavor and fine texture. The cake is carefully prepared and baked, then left overnight in wooden trays to allow its flavors to settle.

It has a moist, soft crumb, a fine texture, and a rich egg flavor, complemented by the sweetness of sugar and honey. It can be served in slices alongside unsweetened Japanese tea, which pairs well with its rich, sweet profile.