Equipment
Ingredients
Dry Ingredients
- 70 g cake flour
- 30 g dutch-processed cocoa powder
- 1 g salt
Wet Ingredients
- 4 eggs, separated, room temperature
- 120 g caster sugar
- 5 ml vanilla extract
Raspberry Filling and Drizzle
- 300 g frozen or fresh raspberries, thawed if frozen
- 50 g granulated sugar
- 15 ml lemon juice, freshly squeezed
- 8 g cornstarch
- 15 ml water, cold
- 100 g fresh raspberries
Nutrition (per serving)
Nutrition is estimated per serving. Nutrients without complete source data are omitted.
Full nutrition
- Calories
- 190 kcal
- Protein
- 5 g
- Carbohydrates
- 38 g
- Fat
- 3 g
- Fiber
- 5 g
- Sugar
- 24 g
- Sodium
- 86 mg
- Saturated Fat
- 1 g
- Trans Fat
- 0 g
- Monounsaturated Fat
- 1 g
- Polyunsaturated Fat
- 1 g
- Cholesterol
- 93 mg
- Potassium
- 217 mg
- Calcium
- 32 mg
- Iron
- 2.0 mg
- Magnesium
- 33 mg
- Phosphorus
- 99 mg
- Zinc
- 0.8 mg
- Vitamin A
- 41 mcg
- Vitamin C
- 14 mg
- Vitamin D
- 0.5 mcg
- Vitamin E
- 0.7 mg
- Vitamin K
- 4 mcg
- Vitamin B6
- 0.1 mg
- Vitamin B12
- 0.2 mcg
- Thiamin
- 0.11 mg
- Riboflavin
- 0.20 mg
- Niacin
- 1.0 mg
- Folate
- 40 mcg
- Water
- 67 g
- Alcohol
- 0 g
- Caffeine
- 3 mg
Sources: Aggregated Public Data, USDA FoodData Central
Method
Preheat your oven to 180°C (350°F). Line the bottoms of two 20cm (8-inch) round cake pans with parchment paper, leaving the sides ungreased so the sponge can grip and rise.
Sift the cake flour, cocoa powder, and salt together into a bowl. Repeat this process twice more to aerate the dry ingredients thoroughly.
In a spotlessly clean bowl, whip the egg whites until soft peaks form. Gradually add 60g of caster sugar while continuing to whip until stiff, glossy peaks are achieved.
In a separate bowl, whip the egg yolks, the remaining 60g of caster sugar, and the vanilla extract until the mixture is pale, thick, and leaves a trailing ribbon when the whisk is lifted.
Gently fold the whipped egg yolk mixture into the stiff egg whites using a silicone spatula, using a large scooping motion to preserve the air bubbles.
Sift the aerated dry ingredients over the egg mixture in three separate additions. Gently fold after each addition just until no dry streaks remain.
Divide the batter evenly between the prepared cake pans and bake at 180°C (350°F) for 15 to 18 minutes. The cakes are done when they spring back to a gentle touch.
Allow the cakes to cool in the pans for 5 minutes, then run a knife around the edges and invert them onto a wire rack to cool completely.
While the cakes cool, combine the 300g of raspberries, 50g of granulated sugar, and lemon juice in a saucepan. Simmer over medium heat until the berries break down and release their juices.
Pass half of the hot raspberry mixture through a fine mesh strainer into a small bowl to extract a smooth coulis for the drizzle. Set the smooth coulis aside to cool.
Return the remaining unstrained raspberry mixture (with seeds) to the saucepan. Mix the cornstarch with the cold water to create a slurry, stir it into the saucepan, and boil for 1 minute until thickened into a jam-like consistency. Remove from heat and cool completely.
Place one cooled cake layer on a serving plate. Spread the thickened, cooled raspberry filling evenly over the top, leaving a small border around the edge.
Place the second cake layer on top. Drizzle the smooth raspberry coulis generously over the cake, allowing some to drip down the sides. Top with the 100g of fresh raspberries before serving.
Chef's Notes
- Fatless sponges derive all their structure and rise from whipped eggs. Ensure your bowls and beaters are completely free of grease before whipping the egg whites.
- Cocoa powder has a tendency to clump more than flour, which is why triple-sifting the dry ingredients is non-negotiable for a light texture.
- Leaving the sides of the cake pans ungreased allows the sponge batter to cling to the walls as it bakes, preventing it from shrinking or collapsing as it cools.
- For the cleanest slices, use a serrated knife and wipe the blade with a warm, damp cloth between each cut.
Storage
Refrigerator: 3 days — Store in an airtight container to prevent the sponge from drying out.
Freezer: 1 month — Freeze the unfilled sponge cakes wrapped tightly in plastic wrap. Do not freeze the assembled cake with the filling.
Troubleshooting
Sponge cake is dense and flat
Cause: Air was knocked out of the egg whites during the folding process, or the dry ingredients were not sifted.
Fix: Cannot be fixed
Prevention: Fold with a light hand using a figure-eight motion, and always sift your dry ingredients at least twice.
Raspberry filling runs out the sides of the cake
Cause: The cornstarch slurry was not boiled long enough to activate, or the filling was assembled while still warm.
Fix: Scrape the filling off, return it to a saucepan, and simmer slightly longer to reduce and thicken.
Prevention: Ensure the filling reaches a rolling boil for 60 seconds after adding the slurry, and cool completely before assembling.
Cultural Context
The fatless sponge, known as 'biscuit' in French pastry, is a foundational cake designed specifically to be light, airy, and highly absorbent. By omitting butter or oil, the cake becomes the perfect canvas to soak up the moisture and bright, acidic flavors of fruit fillings without becoming excessively heavy or cloying.
