Hong Kong Paper Sponge Cake (雞蛋糕)

Light as air and trembling with every jiggle, this personal-sized Hong Kong paper sponge cake is a beloved dim sum–era classic scaled down to a single 3-inch mold. Built on a chiffon-style batter, it bakes inside a paper mold, giving it its signature tall walls and crackled, golden crust with a cloud-soft, cottony interior. The batter is separated — the yolk creamed with oil and milk into a silky base, the white whipped to stiff peaks and folded in — so the whole structure relies on air, making every fold a deliberate act. The reward is a cake that's barely sweet, delicately eggy, and so tender it practically dissolves.

Ingredients

• neutral oil, such as vegetable or canola – 1 tablespoon + 2 teaspoons
• whole milk – 1 tablespoon + 2 teaspoons
• cake flour, sifted – ⅓ cup + 1 tablespoon
• large egg yolks, save whites for meringue – 5 large egg yolks
• pure vanilla extract – ½ teaspoon

• large egg whites, from above, at room temperature – 5 large egg whites
• cream of tartar – ½ teaspoon
• granulated sugar – 6 tablespoons

Instructions

1. Heat the oven to 325°F / 165°C (convection: 300°F / 150°C). Prepare four 4-inch round paper cake molds by setting them on a baking sheet — do not grease them. The paper walls and ungreased surface let the batter cling and climb as it bakes.
2. In a small saucepan over low heat, warm the oil until it registers 175°F / 80°C — it should feel hot to the touch but not smoking. Remove from the heat, add the sifted cake flour all at once, and whisk vigorously until the mixture forms a smooth, cohesive paste with no dry flour remaining.
3. Whisk the milk into the flour-oil paste until smooth, then add the egg yolk, whisking well. Stir in the vanilla. The batter should be pale, smooth, and slightly thick — similar in consistency to a loose pudding. Set aside.
4. In the bowl of a stand mixer fitted with the whisk attachment (or using a hand mixer), beat the egg whites and cream of tartar on medium speed until foamy and opaque, about 45–60 seconds. Increase to medium-high and add the granulated sugar in a slow, steady stream. Continue beating until the meringue holds stiff, glossy peaks — when you lift the whisk, the peak should stand straight up without drooping. This takes about 3–4 minutes total. Watch carefully; the meringue can go from perfect to over-whipped quickly.
5. Add about one-quarter of the meringue to the yolk batter and whisk it in firmly — don't be gentle here. This first addition is a sacrificial lightener: it loosens the dense yolk base so the remaining meringue folds in without being crushed. Switch to a large rubber spatula and add the remaining meringue in two additions, folding with wide, decisive scoops from the bottom of the bowl upward, rotating the bowl as you go. Stop when no white streaks remain and the batter looks airy and uniform.
6. Divide the batter evenly among the four prepared paper molds, pouring from a low height to minimize air loss. Give each mold a gentle tap on the counter to pop any large surface bubbles. Bake for 22–30 minutes, until the tops are deeply golden and crackled, the cakes spring back firmly when pressed, and a skewer inserted in the center of each comes out clean. The tops will dome and crack — that's exactly what you want.
7. Remove the cakes from the oven and immediately invert them — paper molds and all — onto a wire rack. Let them cool completely upside down, about 45 minutes, before flipping upright. Serve at room temperature, pulling the paper away at the table for full effect.