Heat the blackberries in the microwave for 1-2 minutes, then mash with a fork (or meat mallet)
Push through a strainer until you have 1/2 cup of juice.
In a saucepan, whisk together the eggs, egg yolks and sugar combined. Put on the stove and turn the heat on low. Add the butter and blackberry juice. Continue whisking while the curd heats. After about 6-7 minutes you’ll notice it has thickened and is steaming. When you see the first bubble of a simmer start, mix together the lemon juice and cornflour then pour in while whisking constantly. Add some food colouring now if using. Continue to whisk for another couple of minutes until the mixture is thick and you can see the trail from the whisk. Strain into a bowl and place in the fridge to cool.
For the cake
Preheat your oven to 180C / 350F (160C fan) and grease and line 2x 8 inch spring form cake tins.
In a bowl, sift together the flour, cocoa, baking soda, baking powder and salt. Mix well to combine.
In a separate bowl or the bowl of a stand mixer, beat together the melted butter and both sugars until smooth. Add the eggs one at a time, scraping down the sides of the bowl each time and beating well after each. Add the vanilla and beat to combine.
Add 1/3 of the flour mixture to the butter and sugar mixture. Stir through gently until just combined. Now add half of the buttermilk, Mix gently again. Continue like this until all the flour and buttermilk is combined... just. It is important not to overmix or be too heavy handed otherwise your cakes will turn out dense.
Bake for 25-30 minutes until a toothpick inserted comes out with just a couple of sticky crumbs.
Allow them to cool before removing them from the pans.
Make the Ganache
Chop the chocolate into small pieces and put them in a heatproof bowl. While stirring, heat the cream over low-med heat until steaming and bubbles start to appear around the edge. Pour the hot cream over the chocolate and leave it to sit for 5 minutes. Stir the cream and chocolate until fully mixed, thick, smooth and glossy.
Assemble the cake
Once cool, cut the cakes in half so you have 4 layers. Place one layer on your serving dish.
Spread one half of the curd over the first cake layer, the sit another cake layer on top. Spread ganache over the second layer. Sit the third layer on top of the ganache and spread with the remaining curd. Sit the final layer on top and spread the remaining ganache over the top of the cake.
Decorate with berries.
I use a standard Australian 20ml tablespoon (= 4 teaspoons worldwide)
For best results you should always weigh ingredients like flour and sugar. Kitchen scales are relatively cheap but if you can’t weigh the ingredients, use the spoon and level method (don’t scoop).
The Blackberry Curd does require a couple of hours to set firm enough to use between the layers.
This cake recipes scales well and can be halved to make a 2 layer cake or even 12 chocolate cupcakes.
TOOLS USED IN THIS RECIPE
A handheld beater or stand mixer
2x 8 inchspringform tin or cake tins
A silicone spatula makes sure nothing is left behind.