Make this showstopper chocolate layer cake with blackberry Italian buttercream when you really want to impress… Read my tips for perfectly silky Italian meringue buttercream – it really isn’t that scary, I promise!
It feels like it has been YEARS since I posted a layer cake recipe! And I am going to make up for it right now, with this towering chocolate layer cake lusciously filled with blackberry buttercream.
Not ordinary blackberry buttercream either – this is Italian buttercream a.k.a the silkiest and most stable of frostings. It has been years since I made any as I always regard it as a bit, well, scary…
Having now made it twice in as many weeks, I can say it really isn’t scary at all. It does require a little patience and a digital thermometer for best results, but will reward you in wow factor.
Making the chocolate cake
This chocolate cake uses the reverse creaming method. The dry ingredients are pulsed with the butter until you have a sandy/breadcrumb texture. The eggs are added next and finally the milk, until you have smooth batter.
This can be done in a food processor, such as a Magimix, or in a stand mixer fitted with the paddle attachment. As always scraping the bottom and sides of the bowl is mandatory, to make sure everything is blended well.
There’s enough batter here to make a four layer cake if you use 15cm (6in) cake tins. Or you can use a slightly larger cake tins 20cm (9 in) for three layers.
Brushing the still-warm cake layers with a little blackberry syrup will add flavour and moisture to the cake. You could also use simple syrup, made with equal amounts sugar and water.
Making the Italian buttercream
Temperature is key in achieving the perfect Italian buttercream. Start by making the sugar syrup, using a digital or jam thermometer to check it reaches the soft ball stage (120°C/248F).
Beat the egg whites until they form soft peaks then slowly and carefully pour the sugar syrup into the egg whites down the side of the mixing bowl, avoiding the whisk.
Continue to whisk until the meringue is glossy and firm and the mixing bowl cools considerably. If the bowl is too warm, the butter will melt and you will end up with buttercream soup. Do not despair and throw this away… Put in the fridge for 30 minutes and whisk again when butter has cooled.
I used to think that you had to add the butter in small cubes, one piece at a time. Turns out it’s better to add bigger chunks and to continue whisking until the buttercream turns silky and smooth. If it looks like it is curdling, continue to whisk and it should soon come together.
Make sure your blackberry syrup is room temperature before adding. Add a little at a time, testing the flavour as you go on. Italian buttercream can be flavoured with anything from jam, to peanut butter to chocolate. Once you master the basic recipe, it will soon become a favourite.
Italian buttercream keeps for up to a week at room temperature. If you put it in the fridge, it will solidify and may separate when you try to whisk it again. Warm a little of the buttercream in the microwave until liquid and pour it into the remaining buttercream before whisking. Jump over to this article more troubleshooting tips.
Making the blackberry syrup
You can make syrup using any types of red berries, fresh or frozen. I usually frozen berries as they tend to be so much cheaper. The syrup can be drizzled over ice cream, or used to flavour drinks and cocktails, it is quite addictive! Make sure the syrup is at room temperature before adding to the buttercream, otherwise it will melt the butter and undo all our work.
Assembling your chocolate layer cake with blackberry Italian buttercream
I used Russian ball piping tip to create the ruffly effect on this cake. You can use any piping tip or even spread the buttercream over the layers and then cover the entire cake. It is a dream to work with, so smooth and easy to pipe.
Drizzle the blackberry syrup over the cake, letting it drip prettily down the sides. Decorate with fresh flowers such as lilacs or roses to create an incredibly romantic, and incredibly delicious, layer cake.
Chocolate layer cake with blackberry Italian buttercream
For the cake
- 300 g | 2 cups plain flour
- 300 g | 1 3/4 cup soft dark brown sugar
- 50 g | 1/2 cup unsweetened cocoa powder
- 1 tbsp baking powder
- 1 tsp bicarbonate of soda
- ¼ tsp salt
- 200 g | 7oz | 3/4 cup + 1 heaped tbsp cold unsalted butter cubed
- 3 large eggs lightly beaten
- 220 ml | 7.4 fl oz | 1 cup - 1 tbsp whole milk
- 3 tbsp runny honey
- 1 tsp vanilla extract
- 300 g | 12 cups blackberries fresh or frozen
- 150 g 3/4 cup sugar
- Juice of 1 lemon
Italian meringue buttercream
- 360 g | 1 3/4 cups caster sugar
- 1 tbsp honey
- 100 ml | scant 1/2 cup water
- 180 ml | 3/4 cup liquid egg whites or use 6 eggs
- 450 g | 4 sticks unsalted butter at room temperature cut into big chunks
- 3 heaping tbsp blackberry syrup or more to taste
- Pink food colouring optional
- Prepare the blackberry syrup. Put all the ingredients in a saucepan and bring to a simmer over low heat, stirring so the sugar dissolves. Cook for a few minutes, until the blackberries start to burst and release their juices. Strain using a fine sieve, collecting the syrup into a bowl.
- Preheat the oven to 180C (350F). Spray three 15cm (6in) cake tins with cake release spray and line the bottoms with greaseproof paper. The layers will be quite high as there's enough batter for four 15cm (6in) layers. If making four layers adjust baking time to 25-28 minutes.
- Add the flour, sugar, cocoa powder, baking powder, bicarbonate of soda and salt to the bowl of your food processor. Pulse for a minute on low speed to combine.
- Add the cubed butter and mix for 2-3 minutes until the mixture resembles coarse sand.
- Add the eggs and mix for a minute until well incorporated. Use a spatula to scrape the bottom and sides of the bowl to make sure everything is mixed in well.
- Mix the milk and vanilla extract in a measuring jug. Gradually add to the batter, mixing on low speed until combined. Add the honey and mix until you have a smooth glossy batter, scraping the bottom and sides of the bowl as needed.
- Divide the batter between the prepared tins and bake for 35-40 minutes, until the cakes are firm on top and a skewer inserted in the centre comes out clean.
- Cool the cakes in the tins for 10 minutes then turn out to a wire rack to cool. Once cool, level the tops, if needed.
- Make the buttercream. Put the sugar, honey and water in a deep saucepan stir to combine. Bring to the boil over high heat and check the temperature with a digital or jam thermometer. Cook until it reaches 120°C/ 248°F.
- Meanwhile, put the egg whites in the bowl of a stand mixer fitted with the whisk attachment. Whisk at maximum speed until you have soft peaks.
- Carefully pour the sugar syrup into the egg whites, while mixing, down the side of the mixing bowl. Continue to whisk for several minutes until you have a glossy meringue and the bowl feels barely warm to the touch.
- Add the butter, a few chunks at a time, and continue whisking at maximum speed until it is all incorporated. The buttercream may briefly separate or look curdled, but keep whisking and it will soon become glossy and smooth.
- Add the blackberry syrup and mix it in. For a deeper pink colour you can add a little pink food colouring until you have the desired shade.
- Brush the cake layers with any leftover blackberry syrup. Sandwich together with the buttercream, piping or spreading it over the layers.
- Pipe a generous amount of buttercream on top of the cake – I used a Russian ball piping tip to create the ruffles.
- Carefully drizzle any remaining blackberry syrup over the top of the cake, letting it drip down the sides. Serve immediately.