Chocolate Taiwanese Castella Cake Recipe

I just made a Chocolate Castella that’s absurdly fluffy and moist, and once you see its featherlight chocolaty crumb you won’t be able to ignore it.

I’m obsessed with this Chocolate Castella because it’s airy but chocolatey in a way that actually matters. I love how the crumb feels like a Souffle Cake but holds together when you slice it, so you get a clean plate and a grin.

But it’s not delicate theater, it’s bold chocolate with a melt-in-your-mouth softness that makes me reach for seconds. I’m into the science too, eggs separated into yolks and whites do something wild here.

No frills, just that pillowy, chocolaty hit that keeps me sneaking bites all day. Worth every crumb.

I can’t quit it not even trying.

Ingredients

• Egg yolks: Richness and silkiness, basically the cake’s custardy backbone.
• Egg whites: Airy lift and structure, it’s what makes it float.
• Granulated sugar: Sweetness and browning, plus helps stabilize those fluffy whites.
• Whole milk: Tenderness and moisture, it keeps the crumb soft.
• Unsalted butter: Buttery depth and mouthfeel, it’s comfort in fat form.
• Cake flour: Tender crumb and soft texture, nothing dense here.
• Cocoa powder: Chocolate punch without heaviness, nice bitter balance.
• Cornstarch: Lightness and silk, it thins the gluten a touch.
• Cream of tartar: Stabilizes the meringue, so your cake rises evenly.
• Vanilla and salt: Flavor boost and balance, basically makes it taste real.

Ingredient Quantities

• 7 large eggs separated into yolks and whites
• 120 g granulated sugar (about 1/2 cup) divided
• 60 g whole milk, room temp
• 60 g unsalted butter, melted and slightly cooled
• 70 g cake flour, sifted
• 25 g unsweetened cocoa powder, sifted
• 20 g cornstarch
• 1/4 teaspoon cream of tartar
• 1 teaspoon vanilla extract
• 1/4 teaspoon fine salt

How to Make this

1. Preheat oven to 320°F (160°C). Line an 8 inch square pan with parchment, making sure it comes up the sides so you can lift the cake out later.

2. Whisk together the 7 egg yolks, 60 g milk, 60 g melted butter, 1 teaspoon vanilla, 1/4 teaspoon fine salt and half of the sugar (60 g) until smooth and slightly pale.

3. Sift together 70 g cake flour, 25 g unsweetened cocoa powder and 20 g cornstarch into the yolk mixture, fold until just combined and no dry streaks remain. Don’t overmix.

4. In a clean bowl, add the 7 egg whites and 1/4 teaspoon cream of tartar. Begin beating on medium speed until foamy, then slowly add the remaining 60 g sugar in three additions while increasing speed to high.

5. Beat the whites to stiff, glossy peaks. They should hold a firm point but still be shiny. If they look dry you went too far.

6. Gently fold one third of the meringue into the chocolate yolk batter to lighten it, then fold in the remaining whites in two additions using a wide spatula. Use a steady, gentle motion to keep as much air as possible.

7. Pour the batter into the prepared pan, tap the pan on the counter a few times to release large air bubbles, then smooth the top lightly with a spatula.

8. Place the cake pan inside a larger roasting pan and carefully pour hot water into the outer pan to come about halfway up the sides (water bath). Bake at 320°F (160°C) for 50 to 60 minutes, or until the top is set and a skewer comes out with just a few moist crumbs.

9. Turn off the oven, open the door slightly and let the cake sit inside for 10 to 15 minutes to avoid sudden temperature shock. Remove from oven, lift the cake from the pan using the parchment and invert it onto a wire rack to cool completely — flipping it helps keep the top flat and prevents collapse.

10. Once fully cool, peel off parchment, slice with a sharp knife wiped between cuts, and enjoy the soft, moist, fluffy chocolaty crumb. Store in an airtight container; it actually gets better after a day.

Equipment Needed

1. Oven (set to 320°F / 160°C)
2. 8-inch square baking pan lined with parchment (parchment should come up the sides)
3. Large roasting pan or rimmed baking tray (for the water bath)
4. Electric mixer (hand or stand) or a whisk if beating by hand
5. Two mixing bowls (one for yolks, one for whites)
6. Fine mesh sieve or flour sifter (for flour, cocoa and cornstarch)
7. Rubber spatula / wide silicone spatula (for folding)
8. Whisk (for yolk mixture)
9. Wire rack plus a sharp knife (for cooling and slicing)

FAQ

Chocolate Taiwanese Castella Cake Recipe Substitutions and Variations

• Eggs (7 large) → Aquafaba or pasteurized liquid egg: use about 3/4 cup aquafaba (roughly 12 tablespoons) for all 7 whites if you need an egg-free version, or swap whole eggs for equal weight in pasteurized liquid egg for almost the same rise. Texture will be a bit different, but it’s okay.
• Granulated sugar (120 g) → Caster (superfine) sugar or coconut sugar: caster sugar dissolves faster for a silkier crumb; coconut sugar can be used 1:1 but gives a mild caramel note and darker crumb.
• Whole milk (60 g) → Unsweetened soy or oat milk, or watered-down cream: use equal weight for non-dairy swaps; if you want richer cake, use half-and-half or heavy cream thinned with a little water to match 60 g.
• Cake flour (70 g) → All-purpose flour + cornstarch: for 70 g cake flour, use 70 g all-purpose minus about 8 g, then add 8 g cornstarch and sift well. It’ll mimic the lower-protein texture of cake flour.

Pro Tips

1) Use room temp eggs and make sure yolks and whites are totally dry. Cold eggs don’t whip as well so take them out 30 minutes before. Also any tiny bit of yolk in the whites will stop them from ever reaching stiff peaks, so be picky when separating.

2) Add the sugar to the whites slowly once they’re foamy. If you dump it in too fast the meringue will collapse or turn grainy. When you hit stiff glossy peaks stop beating. If the peaks look dry you went too far, if they slump a bit you still got time.

3) Fold like you mean it but be gentle. Use a wide spatula, cut through the center, scoop under and fold over while rotating the bowl. Do one small trial fold first to lighten the yolk batter then finish in two additions. Overmixing kills the air, undermixing leaves streaks.

4) Don’t rush the cooling. The water bath helps but once baked let it rest in the oven with the door slightly open for 10 to 15 minutes, then invert while warm to keep it from collapsing. Use parchment that comes up the sides so you can lift it out cleanly. Store airtight — it actually tastes better the next day.