Green Tea Kasutera (or Castella) Sponge Cake (printable recipe)
Adapted from both this blog and this blog - thanks guys.
According to Emma and wikipedia, Kasutera is a sponge cake that is a specialty of Nagasaki. Per above, Japan as a whole was closed off to the western world for much of its history, but Nagasaki was its trading port and welcomed various trading partners over the years including the Portugese, who brought this sponge cake to Japan. There is no artificial leavening, so the eggs really get a workout. This cake is sweetened with both sugar and honey but is not too sweet and a perfect afternoon tea snack.
8 large eggs
1 and 1/2 cups granulated sugar plus more for sprinkling
1/4 teaspoon of salt
1/8 of a teaspoon cream of tartar
1/2 cup of milk
1/4 cup of honey plus more for top of cake
1 and 1/2 cups all purpose flour
zest of 1 lemon
1 teaspoon vanilla
1 tablespoon plus 2 teaspoons of matcha green tea powder (optional)
- Preheat oven to 325. Line a 9 by 9 inch square baking pan with parchment paper. The paper should come up the sides of the pan. Spray the paper with cooking spray so it sticks to the pan.
- Heat some water in a large saucepan so it is just simmering.
- In the bowl of a standing electric mixer combine the eggs, the sugar, the salt and the cream of tartar.
- Ready for a workout? Place the mixer bowl over the simmering water and whisk the egg mixture together over the heat until light and frothy and warm to the touch, at least six minutes. If you have a handmixer, by all means use it here.
- When the eggs have been warmed sufficiently, put the bowl on the mixer and beat at medium speed with the whisk attachment until the mixture has expanded 2 -3 times in volume and is very pale. If you draw your initials in the batter they should stay there for a few second before fading and the eggs should be of a ribbon consistency. This should take 15 minutes with a standing electric mixer.
- While the egg mixture is mixing, combine the milk and the honey in a microwave safe container and heat for 1 minute. Then stir so that the honey melts into the milk.
- Combine the flour and the lemon zest and toss so that the lemon zest is well incorporated.
- After the eggs have reached the desired volume and color slowly drizzle the milk/honey mixture into the bowl with the mixer on low speed.
- Add the flour/lemon mixture one tablespoon at a time until incorporated.
- Add the matcha and vanilla and mix just until incorporated.
- Pour batter into prepared baking pan and bake for approximately 50 minutes, until a toothpick comes out clean.
- Make a honey syrup by combining a couple of tablespoons of honey with a couple of tablespoons of hot water. Brush this honey water over the cake as soon as it is out of the oven.
- Then, this is weird, before letting the cake cool, transfer the cake (with the parchment paper) into a plastic bag and put in the refrigerator. If this cake dries in the air, it will become dry.
- Let cool in the refrigerator and then slice. The crusts on the side of the cake should be removed.