Preheat the oven to 175oC and line the base of 2 round cake tins with baking parchment.
In a baine marie, melt the chocolate and butter and then leave to cool.
Whisk the eggs and maple until pale, then add the chocolate and vanilla.
Sift the flours, cacao, baking soda and powder, then mix the whole lot together.
Pour the mixture into the prepared tins and bake for about 20 minutes.
When cooked, remove from the tins and allow to cool completely.
To make the buttercream, set the eggs, maple and vanilla in a baine marie and heat to 70oC, then beat until light and fluffy.
Add the butter a tbsp at a time, then the melted chocolate and mix together.
If it’s a little runny (which mine was), allow to cool in the fridge a little first then you should be able to spread it all over the cake without it dripping off!