Pre-heat the oven to 160°C and line and grease an 8 inch round cake tin.
Melt the chocolate in a bain marie or a bowl set over a saucepan of simmering water, then pour into a large mixing bowl.
Add the rest of the ingredients and beat until well mixed.
Pour into the prepared cake tin and bake for 20 minutes.
Remove from the oven and let cool in the tin for 10 minutes before turning and leaving to cool completely before serving.
*Prepare the sweet potato puree by wrapping whole sweet potatoes in tin foil, placing them on a baking tray and baking them for about 45 minutes (depending on the size of your potato). Use a tea towel to help you gauge when they are ready by protecting your hands from the heat as you press down lightly on the surface of the tin foil. They are ready when the potato within feels soft to touch. Remove the potatoes from the oven, leave to cool before unwrapping and scooping out the potato flesh. Stash the flesh in the fridge until ready to use.*You can also use tinned pumpkin puree instead of the sweet potato puree.*Serve with whipped double cream or coconut cream (if you want to keep it dairy free) sweetened with a little maple syrup.