|Nutritional Guidelines (per serving)|
Sponge cake is a light, airy cake that's leavened by the air whipped into the eggs, rather than with baking powder or baking soda.
That means you really need to whip the eggs for a long time—like 10 to 15 minutes. And to get good volume from the egg foam, it helps to warm the eggs and sugar first.
Note that in many cases, cake recipes will generically call for you to spray your pans with baking spray with no explanation for why, or what this step is supposed to accomplish. But with this recipe, since it contains no leavening agents other than the air that is whipped into the egg whites, it is critical to flour the sides of the cake pans so that the batter has something to grab onto as it rises. In this case, the butter or shortening is merely something for the flour to stick to.
In any event, baking spray (i.e. the kind with flour mixed in) will work, as will the manual process of buttering (or greasing with shortening) and then sprinkling the pan with flour. Note that there is no reason to flour the bottom of the pan, as the batter only needs to stick to the sides. A round of parchment on the bottom is all you need to prevent the cake from sticking.
Another tip: Make sure the bowl of your stand mixer is very clean and dry. A tiny bit of oil in the bowl can interfere with the foaming process.
- About 1 1/2 cups (150 grams) cake flour
- About 3/4 cups (150 grams) sugar
- 5 eggs
- 1/2 stick butter (50 grams) melted
- 1 teaspoon vanilla extract
Preheat your oven to 350 F.
Spray two 9-inch cake pans with baking spray (the kind with flour). It can help to line the bottom with a circle of parchment paper cut to fit the pan.
Bring a saucepan of water to a boil on the stovetop, then lower it to a simmer.
In the bowl of your stand mixer, beat the eggs and stir in the sugar until blended. Now set the bowl over the saucepan to form a double-boiler so that the bottom of the bowl is inside the pan but not touching the water. Stir the egg-sugar mixture over the pot until the mixture is warm, which should take 3 to 4 minutes.
Now attach the bowl to your stand mixer and beat with the whip attachment for 10 to 15 minutes or until the mixture is thick and light.
Fold in the flour, then fold in the melted butter. But be gentle, and don't overmix or deflate the foam. Immediately pour the batter into your prepared pans and transfer them to the oven.
Bake for 20 to 25 minutes or until a toothpick inserted into the center comes out clean, or with a crumb or two attached. You can start testing after 20 minutes because it's better to check too soon than to overbake.
Cool the cakes for 10 minutes in the pans on a wire rack, then loosen the edges by running a knife along the sides, turn the cakes out onto the racks and cool for at least another 45 minutes.