½ teaspoon butter
8 egg whites, room temperature
8 egg yolks, room temperature
10 ounces sugar
¼ cup milk
4 tablespoons maple syrup
2 tablespoons mirin
7 ounces bread flour
1 tablespoon maple syrup, for glaze
Preheat oven to 350°F.
Lightly butter the bottom of a 8-inch square cake pan. Line the pan with parchment paper such that the bottom and sides of the pan are covered, and there is an excess of paper at top that can be folded over and used for lifting later.
Using a hand mixer at medium speed beat the egg whites in a bowl until they become foamy. Add the sugar in increments and continue beating until firm peaks form, about 4-5 minutes.
Add the egg yolks one by one and beat at medium low speed until the mixture begins to thicken, about 1 minute.
Add the milk, 4 tablespoons maple syrup and mirin to the egg mixture and blend at medium low speed for about 1 minute.
Add the bread flour in three batches by slowly sifting it into the bowl. Blend until combined making sure that no lumps form and that the mixture is smooth.
Pour mixture into the cake pan to the top. Use a spatula to draw zigzag patterns through the mixture to eliminate air bubbles.
Bake on the middle rack for 45-55 minutes or until the top is evenly browned and firm, and the centre of the cake is dry. Test this by sticking a skewer into the middle of the cake.
Remove baking pan from the oven and brush the top of the castella with maple syrup to make a glaze.
When the castella is cool enough to handle (but still warm), lift it out of the pan using the ends of the parchment paper. Remove the parchment paper and place the cake into a fresh piece of parchment paper. Wrap the cake in plastic wrap. Store in the refrigerator immediately to retain moisture for 4-5 hours.
To serve, cut off the edges of the cake, except the top, and cut into individual rectangles.
Pairs Well With
Brought to Nagasaki by the Portuguese in the 16th century this Japanese sponge cake is usually baked in a wooden frame. Try this simple version with a Canadian twist using maple syrup.