Contents
A thin chocolate cake baked in a large shallow pan and frosted with a hot cocoa icing poured over it while both are still warm, so the frosting sets into the crumb as a fudge layer rather than sitting on top. It feeds twenty-four people from one tin and it is the fastest good chocolate cake there is — no creaming, no layering, no cooling.
What makes it work
- Boil the butter, cocoa and water together and pour it over the flour. This is the defining move. Hot fat and liquid gelatinise some of the starch immediately, which is what gives the cake its dense, almost brownie-like texture.
- Frost it hot. The icing is poured on within five minutes of the cake leaving the oven. The top of the cake and the bottom of the icing merge into a single fudgy layer — that seam is the whole point, and it cannot be achieved by frosting a cold cake.
- A big thin pan and a short bake. 33 × 45 cm, 20 minutes. Baked deeper it is a different, less good cake.
- Buttermilk and soda for tenderness and lift; see buttermilk recipes.
- Pecans on top, immediately, while the icing is still liquid.
Ingredients
One 33 × 45 cm sheet pan. Serves 24.
Cake:
- 250 g all-purpose flour
- 400 g granulated sugar
- 5 g baking soda
- 5 g fine salt
- 225 g unsalted butter
- 40 g cocoa powder — see Cocoa and cocoa mixes
- 240 ml water
- 120 ml buttermilk
- 2 eggs
- 2 tsp vanilla — see Pure vanilla extract
Icing:
- 115 g unsalted butter
- 40 g cocoa powder
- 90 ml milk
- 450 g powdered sugar
- 1 tsp vanilla
- 3 g fine salt
- 150 g pecans, toasted and chopped
Method
Heat the oven to 180 °C / 350 °F. Grease the sheet pan.
Whisk the flour, sugar, soda and salt in a large bowl.
Bring the butter, cocoa and water to a rolling boil in a saucepan and pour it straight over the dry ingredients. Whisk smooth.
Whisk in the buttermilk, eggs and vanilla. Pour into the pan and bake 18–22 minutes, until the centre springs back.
Start the icing five minutes before the cake is due out: melt the butter with the cocoa and milk, bring just to a boil, take off the heat, and whisk in the powdered sugar, vanilla and salt until pourable.
Pour it over the hot cake, tilt to spread, and scatter the pecans immediately.
Cool at least an hour before cutting.
Notes
- It is a sheet cake, so it travels. Bake it in a disposable pan for a potluck and it will be the first thing gone.
- Half the recipe fits a 23 × 33 cm tin at the same temperature for 20 minutes.
- Keeps four days covered, and stays moist because of the fudge seam.
Elsewhere on the site
Method and theory: Cake recipes · cakes · Cocoa and cocoa mixes
Nearby: devils food cake · wacky cake · chocolate bundt cake