Equipment
Ingredients
Chocolate Sponge
- 225 g unsalted butter, softened to room temperature
- 225 g caster sugar
- 4 eggs, room temperature
- 175 g self-raising flour
- 50 g cocoa powder
- 5 g baking powder
- 30 ml whole milk, room temperature
Chocolate Fudge Icing
- 100 g unsalted butter, very soft
- 200 g icing sugar
- 40 g cocoa powder
- 30 ml whole milk
Nutrition (per serving)
Nutrition is estimated per serving. Nutrients without complete source data are omitted.
Full nutrition
- Calories
- 341 kcal
- Protein
- 4 g
- Carbohydrates
- 41 g
- Fat
- 20 g
- Fiber
- 3 g
- Sugar
- 28 g
- Sodium
- 214 mg
- Saturated Fat
- 12 g
- Trans Fat
- 0 g
- Monounsaturated Fat
- 6 g
- Polyunsaturated Fat
- 1 g
- Cholesterol
- 97 mg
- Potassium
- 145 mg
- Calcium
- 80 mg
- Iron
- 1.7 mg
- Magnesium
- 39 mg
- Phosphorus
- 162 mg
- Zinc
- 0.8 mg
- Vitamin A
- 171 mcg
- Vitamin D
- 0.3 mcg
- Vitamin E
- 0.7 mg
- Vitamin K
- 2 mcg
- Vitamin B6
- 0.1 mg
- Vitamin B12
- 0.2 mcg
- Thiamin
- 0.10 mg
- Riboflavin
- 0.15 mg
- Niacin
- 0.8 mg
- Folate
- 40 mcg
- Water
- 19 g
- Caffeine
- 14 mg
Sources: USDA FoodData Central
Method
Preheat the oven to 180°C (350°F) or 160°C (320°F) for fan ovens. Grease a 30x20cm rectangular baking tin and line the base and sides with parchment paper.
In a large mixing bowl, beat the softened butter and caster sugar together until pale, light, and visibly fluffy.
Gradually add the eggs one at a time, beating well after each addition to prevent the mixture from curdling.
Sift the self-raising flour, cocoa powder, and baking powder into the bowl. Gently fold the dry ingredients into the wet mixture using a spatula until just combined.
Stir in the milk until the batter falls easily off the spoon in a soft, dropping consistency.
Pour the batter into the prepared baking tin and level the surface with a spatula. Bake in the center of the oven for 35 to 40 minutes.
Remove the cake from the oven and allow it to cool in the tin for 10 minutes before carefully transferring it to a wire cooling rack to cool completely.
While the cake cools, prepare the icing. Beat the softened butter in a bowl until perfectly smooth. Sift in the icing sugar and cocoa powder, add the milk, and beat everything together until smooth, glossy, and spreadable.
Once the cake has reached room temperature, spread the chocolate icing evenly over the top using a spatula or palette knife. Cut into 15 equal squares to serve.
Chef's Notes
- Ensure all sponge ingredients are at true room temperature. Cold eggs introduced to room-temperature butter will shock the fats and break your emulsion, resulting in a denser cake.
- Sifting the cocoa powder and icing sugar is non-negotiable. Cocoa powder is notorious for holding tight clumps that will not break down in the batter, leaving pockets of bitter, dry powder in your finished cake.
- For an extra layer of flavor complexity, replace the milk in the sponge with an equal amount of strongly brewed hot coffee. It will deepen the chocolate flavor without making the cake taste like coffee.
- Do not overmix the batter once the flour is added. Overworking the flour activates the gluten, which will turn a light and fluffy sponge into a heavy, tough cake.
- The dropping consistency is key. When you lift a spoonful of batter, it should drop off the spoon under its own weight after a second or two. If it stubbornly sticks to the spoon, add another tiny splash of milk.
Storage
Refrigerator: 5 days — Store in an airtight container. Bring to room temperature before serving for best texture.
Freezer: 3 months — Freeze un-iced for best results. Wrap the cooled sponge tightly in plastic wrap and a layer of foil.
Troubleshooting
Batter curdles when eggs are added
Cause: Eggs were too cold or added too quickly
Fix: Add a tablespoon of the measured flour to the batter and beat vigorously to bring the emulsion back together
Prevention: Ensure all ingredients are at room temperature and add eggs one at a time
Cake is dry and crumbly
Cause: Overbaking or using too much flour
Fix: Cannot be fixed, but can be masked by brushing the warm cake with a simple sugar syrup before cooling
Prevention: Weigh dry ingredients carefully with a digital scale and check the cake 5 minutes before the minimum suggested baking time
Icing is too stiff to spread and tears the cake
Cause: Butter was not soft enough or too much icing sugar was used
Fix: Beat in extra milk, half a teaspoon at a time, until the icing reaches a soft, spreadable consistency
Prevention: Ensure butter is properly softened before making icing
Cultural Context
The traybake is a quintessential British baking staple, beloved for its straightforward preparation and generous yield. It gained immense popularity in the mid-20th century as home baking became a common family activity and a reliable centerpiece for school bake sales and community fetes. By baking the sponge in a shallow, rectangular tin, the cooking time is reduced and portioning becomes incredibly simple, cementing its status as the ultimate egalitarian dessert.
