The taisan is so named because it resembles the local brick-shaped knife sharpener.
For the egg white mixture:
8 egg whites (about 1 cup)
1/2 teaspoon cream of tartar
3/4 cup granulated sugar
For the egg yolk mixture:
1-3/4 cups cake flour or 1-1/2 cups all purpose flour
1/2 cup granulated sugar
1 tablespoon baking powder
1 teaspoon vanilla
1/2 cup water
1/2 cup melted butter
5 egg yolks (about 1/3 cup)
Preheat the oven to 350 °F or 175 °C.
Line the bottoms of three 8x3x3-inch loaf pans or two 9-1/2x5-1/2x3-inch loaf pans with wax paper.
In a separate dry, clean bowl, beat at highest speed of an electric mixer the egg whites with the cream of tartar. When the mixture has fine bubbles or the mixer leaves fine lines on the egg white mixture, gradually add in the sugar. Continue beating for three more minutes if using Kitchen Aid, or four minutes more for an ordinary hand mixer.
Put together in a bowl the egg yolks and all other ingredients. Beat well with a mixer for about two minutes.
Pour the yolk mixture into the egg whites. Gently fold with a wire whisk.
Pour the batter into the prepared pan. Smoothen the cake batter with wire whisk to remove any air bubbles.
Bake for 30 to 35 minutes if using 8x3x3-inch pans, or 45 minutes if using 9-1/2x5-1/2-inch pans.
Cool. Loosen the sides of the cake with a metal spatula. Remove the wax paper.
When totally cool, brush the cakes with 1/3 cup melted butter. Sprinkle with 1/4 cup sugar.
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To make a mocha taisan, omit the vanilla. Add one teaspoon instant coffee.
For a pandan taisan, replace the vanilla with one teaspoon pandan flavoring.