“There is a kind of alchemy in the transformation of base chocolate into this wise fool’s-gold, a layman’s magic” Chocolat,
ver
I love the ease of this very simple chocolate cake. Made with only a few cupboard staples it offers maximum reward for minimum effort and has everything you look for in a good chocolate cake: rich, dark and moist, with just a hint of bitterness from the coffee while the frosting sits somewhere between a buttercream and a mousse with a lightly aerated texture. To finish, if desired, the light scattering of salt to top contrasts against the sweetness and enhances the flavour beautifully.
NOTES
– There is more buttercream here than is strictly speaking necessary – it is over indulgent. Most chocolate fiends could happily make two thirds or even half the quantity and still not feel cheated, so feel free to reduce the quantity first time round for future judgment.
– Quality ingredients always make all the difference. This recipe calls for Dutch-process cocoa which I tend to prefer to natural cocoa powder in recipes where possible – note that they are not necessarily interchanged without poor consequences on the bake. The predominant reason for preferring Dutch-process cocoa is that it’s treated with a solution that neutralises the acidity and results in a much darker, smoother and more intense flavour than it’s non-Dutch sibling. It also usually means superior quality. Being a specialty product, the quality of the bean and processing is almost always superior. While natural cocoas frequently come from low quality beans squeezed dry of every last drop of cocoa butter producing a starchy, low fat chocolate about as rich and tasty as chalk, by contrast most Dutch-process cocoa brands contain twice the amount of fat at least and come from far superior beans, resulting in a product that’s higher in fat, lower in starch, and more aromatic all around, with a deep mahogany hue and a flavour profile that underlines cocoa’s beautiful dark, nutty tones. If unsure, can recommend Valrhona, Bensdorp and Callebaut which are excellent quality brands.
As a side note, in case you are forced to substitute for whatever you have in the cupboard for this or any recipe, here’s what to expect for a 1-to-1 substitution:
Using natural cocoa instead of Dutch-process.
- Bakes will be lighter, tawny rather than mahogany
- Since the baking powder is necessarily doing the leavening on its own without the cocoa (the Dutch-process would have been neutral), the bake should rise just fine
- The flavour may be little more bitter due to natural cocoa’s acidity which may not be entirely neutralised by the remaining ingredients in the recipe.
How to adjust the recipe to minimise effects: If the recipe calls for three tablespoons of cocoa or less, don’t make any further adjustments. If more than three tablespoons, replace the baking powder with half the amount of bicarbonate of soda, leaving the remaining ingredients the same. Because bicarb is a base, this switch will neutralize the acidity in the natural cocoa, improving the flavour. Note: If the recipe already calls for baking soda as well as baking powder, there’s no need to make any change save substituting the cocoa.
Using Dutch-process cocoa instead of natural.
- Bakes will be darker, mahogany rather than tawny.
- Without the acidity of the natural cocoa, the baking soda in the recipe won’t react as strongly and the texture may reflect this: cakes may not rise so well, and cookies may be a little more stodgy.
- The flavour may be a little soapy if the baking soda hasn’t been fully neutralised due to the lack of acid in the Dutch-process.
How to adjust the recipe to minimise effects: Replace the baking soda with twice the amount of baking powder, leaving the remaining ingredients the same. This change will help your baked goods rise, since without the acid in natural cocoa you need a leavener that provides the necessary rise all on its own, i.e. baking powder. Note: If the recipe calls for baking powder as well as baking soda, or if it calls for vinegar or another acidic ingredient, there’s no need to make any change save substituting the cocoa.
– Since brewed coffee is added to the frosting it’s important to ensure the coffee is completely cool before incorporating. If too hot, it could melt the butter and split the frosting. You can usually bring this back with enough beating.
DARK CHOCOLATE SHEET CAKE
WHAT YOU’LL NEED
Equipment:
- electric hand or stand mixer (we used our KitchenAid)
- 32 x 22 cm rectangular baking tin, lined with baking parchment
Serves: 14-18
INGREDIENTS
For the chocolate cake:
- 1 tbsp. instant coffee granules
- 100 ml boiling water
- 200 g plain flour
- 65 g Dutch-process cocoa powder
- 1 tsp bicarbonate of soda
- ¾ tsp baking powder
- ½ tsp salt
- 275 g granulated sugar
- 220 ml buttermilk
- 100 ml melted butter
- 2 large eggs
- 1 tbsp. vanilla bean extract
For the frosting:
- 1 tsp. instant coffee granules
- 50 ml boiling water
- 110 g dark chocolate (minimum 70% cocoa recommended), finely chopped
- 170 g unsalted butter, room temperature
- 200 g icing sugar, sifted
- 100 g Dutch-process cocoa powder
- 2 tbsp double cream
- 1 tsp vanilla bean extract
- ¼ tsp salt
Optional extras if desired: (not used in ours above)
- sprinkles, chocolate chips or fresh raspberries to decorate
METHOD
Preheat the oven to 180°C/160°C Fan/1Gas mark 4. Grease and line a 32cm x 22cm tin with baking paper.
- Place the instant coffee granules and boiling water into a measuring jug. Stir until the granules are dissolved. Set aside to cool, until required.
- Meet the butter in a small saucepan and set aside to cool, until required.
- In a large mixing bowl, whisk together the flour, cocoa powder, baking soda, baking powder and salt, until evenly combined. Incorporate the sugar.
- Pour the buttermilk, cooled melted butter, eggs and vanilla bean extract into the mixing bowl with the dry ingredients. Whisk, until evenly combined and glossy. Pour in the brewed coffee and whisk until smooth. The batter should be thin and runny. Pour the batter into the prepared baking tin.
- Bake, for 30 or until risen and a skewer inserted into the middle comes out with a few moist crumbs attached.
- Remove from the oven and allow to cool in its tin for 10 minutes, before carefully turning it out and onto a wire rack to cool fully before frosting.
For the frosting:
- As before, place the instant coffee granules and boiling water into a measuring jug. Stir until the granules are dissolved. Set aside until completely cool.
- Place the finely chopped dark chocolate into a Bain Marie – a heatproof bowl set over a saucepan filled with a few centimeters of barely simmering water. Do not let the base of the bowl touch the water. Heat, stirring often, until the chocolate is completely melted and smooth. Remove the bowl from the heat and set it aside to cool.
- Meanwhile, in the bowl of a stand mixer fitted with the beater attachment, beat together the butter and sugar, on medium speed, until light and creamy. Pause mixing to scrape down the bottom and sides of the bowl as needed. This should take a good 5 minutes for a fluffy result.
- Pour in the melted and cooled dark chocolate. Increase the mixer speed to medium-high and beat until well combined, 2 more minutes. Again, pause to scrape down the bottom and sides of the bowl to ensure thorough mixing.
- Add in the cocoa powder, cream, vanilla bean extract and salt. Beat until just combined then pour in the cooled coffee. Set the mixer speed to high and beat for a further 2 minutes, until very smooth and fluffy.
For assembly:
When you’re ready to serve, set the cake out on a serving plate or cake stand. Using an offset spatula or the back of a metal spoon, spread the frosting generously in swirls over the top of the cake. Sprinkle over a little of your chosen salt flakes, before slicing and serving.
This cake keeps beautifully in an airtight container and stored at room temperature for a few days.
