Pre-heat the oven to 160°C and line and grease 2 x 8 inch round cake tins.
Melt the chocolate in a bain marie then set aside.
In a separate large mixing bowl whisk together the flours, cocoa powder, bicarbonate of soda, coffee and salt and set aside.
In another bowl (or a stand mixer) beat together the buttermilk, the sugars, olive oil, eggs and vanilla then add the flour mixture and beat until combined.
Pour in the melted chocolate and mix in until fully incorporated.
Divide the batter evenly between the two cake tins then place in the oven and bake for 30-35 minutes.
Turn out the cakes and cool on wire racks before filling and decorating.
Beat together the butter and sugar for about 10 minutes in a stand mixer until light and fluffy.
Add cocoa, melted chocolate, clementine juice, salt and vanilla extract and beat into the creamed butter and sugar until everything is smooth and evenly combined.
Pour the 120g of caster sugar into a medium saucepan with the water. Bring to a low boil until the sugar dissolves.
Remove from the heat and allow to cool for 10 minutes.
Pour in the cranberries and stir to coat evenly with the sugar syrup.
Place in the fridge overnight.
The next day remove the cranberries from the syrup with a slotted spoon, pat dry with a kitchen towel then spread out evenly onto a plate.
Sprinkle over the remaining 60g of caster sugar and gently roll the cranberries so they are totally coated with sugar.
Leave to dry for at least an hour before using.
Caramelised Clementine Slices
Pour caster sugar into a medium saucepan with the water. Bring to a low boil until the sugar dissolves.
Cut the clementines into thin slices then submerge into the sugar syrup. Bring the syrup back to a boil then simmer for 5 minutes. Turn the heat off.
Remove the clementine slices from the sugar syrup (reserve the syrup for clementine bellinis on Christmas morning*) with a slotted spoon then place on a baking tray lined with greaseproof paper. Bake for 10 minutes at 150°C. Turn the slices over and bake for a further 10 minutes. Remove from the oven and cool before you use them to decorate.
Place one of the sponge layers on a cake board and pipe a circle of buttercream at the very edge of the top of the cake to act like a dam for the cranberry sauce.
Spread the cranberry sauce on top of the sponge, right to the edges of the buttercream dam.
Place the second sponge layer on top and cover the top and the sides of the cake with the buttercream.
Decorate the top of the cake with the sugared cranberries and candied clementines.
*If you don’t have any Cranberry Clementine Sauce to hand then improvise using any leftover cranberry sauce, homemade or shop bought, warm up in a small saucepan with the zest of 1 clementine and leave to cool until needed. *To make Clementine Bellinis all you need is 1 tablespoon of the clementine syrup at the bottom of your champagne glass and top it up with plenty of fizz.