Recipe details
Ingredients
For the cake:
- 170g plain flour
- 1 tsp baking powder
- 1/4 tsp bicarbonate of soda
- 200g light brown sugar
- 200g golden caster sugar
- 200g dark chocolate
- 200g unsalted butter, cubed
- 1 tbsp instant coffee granules
- 25g cocoa powder
- 3 medium eggs or 2 large
- 75ml buttermilk (see notes below for a substitute)
For the Buttercream:
- 300g butter, room temperature
- 550g icing sugar, sifted
- 70g cocoa powder
- 75ml double cream, with one tsp coffee granules stirred in (see notes below)
- 1 tbsp vanilla extract
Instructions
- Heat your oven to 160ºc and grease and line two 6 inch cake tins.
- In a large mixing bowl combine the flour, baking powder, bicarbonate of soda, light brown sugar, golden caster sugar and cocoa powder. Lightly whisk to remove any lumps and put to one sde.
- Roughly chop the dark chocolate and put it in a medium pan with the butter.
- Mix your coffee granules into 120 ml of water and add to the pan.
- On a low-medium heat, gently melt the contents of the pan until fully dissolved.
- Crack your eggs into a small bowl, add the buttermilk and whisk briefly to combine.
- Pour the egg mixture, and the melted chocolate mixture, into the mixing bowl with the dry ingredients and stir everything until you have a smooth batter and no dry flour remains.
- Divide evenly between the two cake tins (see notes for atip) and bake for 1 hour 20 minutes. Insert a skewer and if it comes out clean, it's ready. If not continue baking and checking every five minutes.
- Leave to cool for 5 minutes in the tin, carefully remove, then leave to cool completely.
Prepare the Buttercream
- Add the butter to a standing mixer (alternatively, use a hand mixer) and beat briefly, breaking it down until smooth.
- Sift in the cocoa powder and half of the icing sugar. Start the mixer on the lowest setting and once most of the dry icing sugar has been combined, add the remaining half.
- Slowly add the cream mix, the vanilla and then once it's mostly incorporated, beat on a high speed for 4-5 minutes. You should have a smooth, creamy buttercream. (see notes to troubleshoot)
Decorate the Cake
- First, check if your sponges are level. If they’re uneven, carefully trim the tops with a sharp knife. Begin by spreading a layer of buttercream in the centre of the first sponge, smoothing it out to the edges. Place the second sponge on top and repeat the process. Using an offset spatula, apply a light crumb coat of buttercream over the entire cake. This doesn’t need to be perfect - just seal any gaps between the layers and smooth it out. Let it set for 10-15 minutes, then apply a thicker coat of buttercream, covering any remaining patches and ensuring an even finish.
- Once you're satisfied with the buttercream layer, transfer the remaining buttercream into a piping bag fitted with a large star nozzle. Pipe decorative swirls around the edge of the cake, and fill the center with something like raspberry or cherry jam for a pop of flavour.
- Now for the fun part - decorating! I have given a simplistic way of finishing this above, I also tried decorating it with flowers and raspberries which went turned out beautifully too. Depending on your celebration you could decorate your cake many ways (see notes)
Ways to elevate a simple cake for a celebration
Birthday: Add colourful sprinkles, edible glitter, or custom cake toppers.
Anniversary: Pipe elegant buttercream roses or add fresh flowers.
Holidays: Top with seasonal sweets and chocolates (like candy canes for Christmas) or festive shapes made from fondant.
Children’s Party: Use chocolate ganache drips with bright decorations or cartoon-themed toppers.
Elegant Event: Dust with cocoa powder or powdered sugar and add chocolate curls or shards for a refined look.
Casual Gathering: Finish with whipped cream, fresh berries, and a drizzle of caramel or chocolate sauce.
I don't have buttercream, what can I use instead?
As long as you have milk and lemon to hand, it's eay to make a quick homemade buttermilk.
To make buttermilk from milk and lemon juice:
Pour 235ml of milk into a measuring cup or bowl. Add 1 tablespoon of lemon juice (or white vinegar) to the milk. Stir the mixture and let it sit for 5-10 minutes until it curdles slightly and thickens.
Your homemade buttermilk substitute is ready to use! Just str I the fire as you would buttermilk.
Alternatively, try using thick Greek yoghurt or sour cream
Troubleshooting tips for buttercream
I your buttercream isn't lookng as you'd hoped, here are some ways to fix it:
If your buttercream is too stiff or hard to spread, add a small amount of milk, cream, or water—one teaspoon at a time—mixing until it softens. On the flip side, if it’s too soft or runny, chill it in the refrigerator for 15-20 minutes to firm it up. You can also add more sifted powdered sugar to thicken the mixture, but be cautious of making it too sweet.
If your buttercream has a grainy texture, it may be due to undissolved sugar or butter that wasn’t properly softened. In this case, warm the bowl slightly over a water bath while whisking until smooth, or re-whip it with softened butter.
If it appears too airy or full of bubbles, beat the buttercream on low speed for a few minutes to eliminate excess air and achieve a smoother texture. Lastly, if your buttercream looks greasy or separated, place it in the fridge for 10-15 minutes, then re-whip it on low speed.
Tip for even cake layers
Whenever I start making cake mix for two or more sandwich tins, the first thing I do is weigh my mixing bowl and write it down. I then weigh it again when I am ready to pour it into the tin and divide by however many layers I am making. I then have an exact figure to weigh into each tin to ensure they are all even.
