Recipe courtesy of Psychologies Magazine (October 2016) and taken from Twist: Creative Ideas to Reinvent Your Baking by Martha Collison.  

Ombre cakes are so elegant, and much simpler than people think.  The buttercream gets its pinky hue from blackberry syrup, rather than food colouring, so you get their delicate flavour in each bite.  The honeycomb should be put on top just before serving.  

The recipe below just provides all the information you need for finishing the cake, you will need to make up two batches of your favourite chocolate cake and divide between three tins.

Serves : 10-12

For the cake :
Butter, for greasing
2 x your favourite Chocolate Cake recipe

For the Jam :
150g blackberries
100g caster sugar

For the Honeycomb :
100g caster sugar
4 tblsp golden syrup
1 1/2 tsp bicarbonate of soda

For the Buttercream :
250g unsalted butter, softened
600g icing sugar
1 tsp milk

To decorate :
12 blackberries, plus mint leaves (optional)

Step One : Make two batches of your chocolate cake recipe and divide it between three 18cm tins.  Bake in the oven as per the recipe instructions until risen and an inserted skewer comes out clean.  Leave them to cool in the tins for 10 minutes before turning out on to a cooling rack.

Step Two : To make the blackberry jam filling, put the blackberries, the sugar and 50ml of water into a small saucepan and simmer for 15 minutes.  Stir the mixture often, gently crushing the blackberries so that they release their intense colour.  Drain the purple syrup through a sieve into a small heatproof jug, and reserve the pulp, or jam, to fill the cakes.

Step Three : To make the honeycomb, put the sugar and golden syrup into a medium saucepan.  Boil until it turns a dark golden colour, then remove from the heat and quickly whisk in the bicarbonate of soda. The mixture will froth up while it is extremely hot, so be careful.

Step Four : Pour the honeycomb on to a piece of baking parchment and leave to harden before breaking into shards.

Step Five : To make the buttercream icing, beat the butter and icing sugar together until smooth and light.  This will take around 10 minutes with an electric, hand-help whisk.  Put a third of the icing into a small bowl and add five teaspoons of the blackberry syrup.  Repeat with another third of the icing in a separate bowl, only using one teaspoon of syrup this time.  If the icing splits, add a few more tablespoons of icing sugar and it should come back together.  Add the milk to the remaining white icing to loosen it slightly.  You should now have three different shades of icing, all the same consistency.

Step Six : Take the cooled sponges and sandwich them together with a little of the white icing and the pulp left over from making the syrup.  Cover the top and sides of the top layer of the cake with the white icing, applying it thickly, as a lot will be scraped off later.

Step Seven : Cover the bottom third of the cake with a thick layer of the darkest icing, then fill in the gap between the two colours with the pale purple icing.  Use a large palette knife, set at a 40o angle to the cake, to scrape off the excess icing and create a smooth finish.  The colours should blend together slightly, creating the ombre effect.

Step Eight : Transfer the leftover icing into a piping bag fitted with a closed star nozzle.  You can gently mix all the colours together to get a rippled effect.  Pipe a wiggly border around the top of the cake, then decorate with honeycomb, blackberries and a few mint leaves, if you like.