Pre-heat oven to 160°C and line and grease 2 x 8 inch round cake tins.
Melt the chocolate in a bain marie or a bowl set over a saucepan of simmering water, then set aside.
In a large mixing bowl whisk together the flours, cocoa powder, espresso powder, bicarbonate of soda and salt until well mixed.
In a separate bowl mix together the buttermilk, sugars, olive oil, eggs and vanilla then beat into the flour mixture.
Finally mix in the melted chocolate until completely incorporated.
Divide the mixture between the 2 cake tins and bake in the oven for 30-35 minutes until an inserted cocktail stick comes out clean.
Turn out the cakes and cool on wire racks before covering with buttercream.
Raspberry Swiss Meringue Buttercream
Heat the egg whites and caster sugar in a bain marie, or a bowl set over a saucepan of simmering water, stirring constantly until the sugar has dissolved and the temperature has reached 71°C.
Remove the egg whites and sugar from the heat and pour into a stand mixer with a whisk attachment. Whisk until the meringue forms firm peaks.
Change the attachment to a paddle attachment. On a low speed add the butter slowly cube by cube. When you have almost added all the butter the mixture will look curdled. Do not fret – this is supposed to happen and just means you are nearly done. Just continue to add all the butter. Once the butter is totally incorporated the buttercream will miraculously become a smooth velvety consistency.
Make the raspberry puree by tipping all the raspberries into a blender and blending on high for a couple of minutes. Press the puree through a sieve to remove the seeds.
Then add the raspberry puree to the buttercream along with the vanilla extract and salt. At first the buttercream will look curdled again but just mix for a couple of minutes until it returns to its smooth state.
Spread the buttercream in an even layer over one of the chocolate cakes, then place the second chocolate cake on top.
Smooth out the buttercream squidging from the centre of the cakes with a palette knife to create the naked effect.
Pipe buttercream roses on top of the cake until completely covered.
You can keep the cake in the fridge until needed but do serve the cake at room temperature.