Direct answer: Hong Kong paper-wrapped sponge cakes stay tall and fluffy when egg whites are whipped to medium-stiff peaks, the yolk batter is smooth, and the two mixtures are folded together without crushing the foam. Bake immediately at 340 F/170 C for 22 to 26 minutes in tall parchment collars, then cool on a rack so trapped steam does not make the crumb gummy.
Key takeaways
- Use cake flour for a fine, tender crumb.
- Keep every bowl and whisk for egg whites completely grease-free.
- Whip to glossy medium-stiff peaks, not dry clumps.
- Fold in three additions and stop as soon as no white streaks remain.
- Fill tall parchment collars two-thirds full and bake without delay.
What is Chinese paper-wrapped sponge cake?
Paper-wrapped sponge cake, often called zhi bao dan gao, is an old-school Hong Kong bakery cake baked as a tall individual portion inside a pleated parchment collar. It has an egg-forward aroma, a lightly browned cracked dome and a very soft chiffon-like interior.
It is not a frosted cupcake, steamed egg cake or Japanese castella. The height comes mainly from whipped egg foam, while a small amount of oil and milk keeps the crumb tender after cooling.
Ingredients for six cakes
- 4 large eggs, about 200 g without shells, separated while cold
- 3/4 cup/90 g cake flour
- 1/2 teaspoon baking powder
- 1/4 teaspoon fine salt
- 1/3 cup/65 g granulated sugar, divided
- 1/4 cup/60 ml whole milk, room temperature
- 3 tablespoons/45 ml neutral oil
- 1 teaspoon vanilla extract
- 1/4 teaspoon cream of tartar or 1 teaspoon lemon juice
Allow about 25 minutes preparation, 22 to 26 minutes baking and 45 minutes cooling. You also need six 3-inch/7.5-cm ramekins or sturdy metal rings, parchment paper, two bowls, a hand or stand mixer, whisk and flexible spatula.
Make the paper collars
Cut six parchment rectangles about 8 by 6 inches/20 by 15 cm. Fit each sheet into a ramekin so the paper rises 2 inches/5 cm above the rim. Pleat the sides where necessary; do not staple or tape parchment that will enter the oven.
The ramekin supports the cake while the tall paper guides its rise. Thin cupcake liners alone spread outward and produce short cakes. Place all molds on one flat baking sheet before mixing.
Step 1: heat the oven
Set a rack in the lower-middle position and preheat to 340 F/170 C conventional, or 320 F/160 C fan. Give the oven at least 20 minutes to stabilize. An oven thermometer is useful because excessive heat sets and splits the top before the center can expand.
Step 2: make the yolk batter
Whisk four yolks with 20 g of the sugar until smooth. Add milk, oil and vanilla and whisk until the mixture looks evenly emulsified, with no oil beads.
Sift cake flour, baking powder and salt directly over the bowl. Whisk gently just until smooth. Do not beat after the flour disappears; excess gluten makes the cake chewy and encourages tunnels.
Step 3: whip the egg whites
Place four whites in a clean dry bowl. Beat at medium speed until foamy, then add cream of tartar. Add the remaining 45 g sugar in three portions over about 2 minutes.
Continue beating at medium-high speed until the foam is glossy and a lifted whisk makes a peak whose very tip bends slightly. This is medium-stiff peak stage. Stop before the whites look dry, grainy or broken.
Step 4: lighten and fold
Whisk one-third of the meringue into the yolk batter to lighten it. Add half the remaining meringue and fold with a spatula: cut down through the center, sweep across the bottom and turn the batter over. Rotate the bowl and repeat.
Fold in the final portion only until no white streaks remain. Scrape the bottom where dense yolk batter hides. The finished batter should flow in a broad ribbon and hold visible volume; a thin runny batter has lost too much air.
Step 5: fill the collars
Divide batter among the six collars, filling each about two-thirds full. A scale gives equal portions of roughly 65 to 70 g. Run a wooden skewer through each cup once to break only large air pockets, then tap the tray lightly one time.
Bake immediately. Leaving foam on the counter allows bubbles to merge and collapse, which creates a dense layer near the base.
Step 6: bake
Bake for 22 to 26 minutes. Do not open the door during the first 20 minutes. The cakes are ready when the domes are golden, spring back after a light touch and a skewer comes out without wet batter.
For an objective check, the center should reach about 200 to 205 F/93 to 96 C. If tops brown too quickly while centers remain wet, reduce the next batch by 10 F/5 C rather than covering early and disturbing the rise.
Step 7: cool correctly
Move the cakes, still in their ramekins, to a rack for 5 minutes. Lift them out by the parchment and cool upright for another 35 to 40 minutes. Air must circulate beneath and around the paper.
A small amount of settling is normal. Severe collapse usually means underbaking, under-whipped whites or rough folding. Do not seal warm cakes; condensed steam makes their sides sticky.
How to get a finer crumb
Use room-temperature yolk batter ingredients so oil and milk combine evenly. Whip whites at medium speed for smaller, more stable bubbles before finishing at medium-high. Fold deliberately rather than stirring in circles.
Weigh flour and sugar. Scooped flour can be overpacked, while too little sugar weakens the foam. A few natural cracks are characteristic; the goal is a moist fine interior, not a perfectly smooth dome.
Substitutions
All-purpose flour
For 90 g cake flour, use 78 g all-purpose flour plus 12 g cornstarch, sifted twice. The crumb may be slightly less delicate.
Dairy-free milk
Use unsweetened soy milk in the same quantity. Oat milk also works but may add mild sweetness. Avoid thick coconut cream because it weighs down the foam.
No cream of tartar
Use 1 teaspoon lemon juice. It helps stabilize the whites but does not replace correct whipping.
One round cake
This formula can bake in an ungreased 7-inch/18-cm chiffon pan, but baking time and cooling method change. Do not use a greased solid cake pan and expect the same height.
Common mistakes
The cakes collapse deeply
The center was underbaked or the foam was weak. Confirm spring-back and a clean skewer before removing the tray.
A dense layer forms at the bottom
The yolk mixture was not fully incorporated, or the batter waited before baking. Scrape the bowl bottom during the last folds and fill prepared molds immediately.
The crumb is rubbery
Too much flour or aggressive mixing developed gluten and deflated the foam. Weigh flour, sift it and stop folding promptly.
Large holes run through the cake
The meringue was over-whipped or large bubbles were left in the cups. Aim for glossy peaks and pass a skewer once through each filled collar.
The paper sticks
Peeling while hot tears the moist crumb. Cool completely, then pull the parchment slowly outward rather than straight up.
Food safety and storage
Use clean hands and utensils when separating raw eggs, and keep shell fragments out of the bowls. Do not taste raw batter. Bake until no wet batter remains; the 200 to 205 F/93 to 96 C center used for doneness is well above the temperature needed to set the egg-rich crumb.
Cool within 2 hours. Store plain cakes airtight at room temperature for 1 day or refrigerate for up to 3 days. Refrigerate sooner in a very warm or humid kitchen. Let chilled cakes stand 20 minutes before serving. Freeze individually wrapped cakes for up to 1 month and thaw while wrapped.
Related lessons
For more Hong Kong bakery practice, compare the meringue structure here with Hong Kong pineapple buns and the filled enriched dough in cocktail buns. If you prefer a steamed brown-sugar sponge, see Cantonese ma lai go.
Recipes4Less cooking courses demonstrate medium-stiff peaks, efficient folding and visual doneness cues so beginners can distinguish stable foam from under- or over-whipped meringue.
FAQ
Why are paper-wrapped cakes not very sweet?
The style emphasizes egg aroma and light texture. This formula uses enough sugar to stabilize the foam without producing a Western-style cupcake sweetness.
Can I use whole eggs without separating them?
Whole-egg sponge methods exist, but they require different temperatures and mixing. Separating the eggs gives beginners a clearer, more controllable route to a tall chiffon-like crumb.
Why do the tops crack?
Gentle cracking is traditional and comes from rapid expansion inside the tall collar. Very deep splits with wet centers suggest excessive oven heat.
Can I steam this batter?
No. Steaming changes the crust, moisture and structure. Use a recipe designed specifically for Chinese steamed egg cake.
Can I make the batter ahead?
No. Whipped foam loses volume while standing. Prepare the collars first, then mix, portion and bake immediately.
Conclusion
Successful Chinese paper-wrapped sponge cake depends on stable glossy meringue, gentle complete folding and immediate baking in tall parchment collars. Use cake flour, verify the center is fully baked and cool the cakes with air circulation. The result is a lightly sweet, egg-fragrant bakery cake with a tall golden dome and fine fluffy crumb.