500gmSweet Potatounpeeled uncooked weight – you might need two
350gmdark chocolatecut into pieces
Oven 170 C / 350 F deg, to bake the cake / 8 inch cake tin – 20 cm. 200 C / 180 F to bake the sweet potato
Put the flour, baking powder and sugar in a bowl with the cocoa powder.
Add the water, vanilla, oil and vinegar. Mix until a smooth batter is formed
Pour into a lined round tin. Bake gently for 30-40 minutes or until cooked in the centre when tested with a toothpick. If you have a hot oven bake at 160 C.
The Sweet Potato ganache
Break or chop the chocolate up into tiny pieces and put into a bowl. Scoop out the potato and put into the bowl with the chocolate and mix till melted. Use a hand mixer to give the ganache a beating and cool it down
You can peel and put the potato into a food processor and whizz till smooth and the chopped chocolate and process till smooth.Make sure the sweet potato is hot. This will melt the chocolate.
The ganache will get firmer as it cools so if you want to pipe do it straight away.