To Make the Cake

1. Preheat the oven to 200c (fan). Wrap the sweet potatoes in tin foil and place on a baking tray before placing in the oven to roast for 1 hour. Remove form the oven, unwrap and leave to cool for 20 minutes. 
2. Slice the sweet potatoes in half and scoop out the flesh. Transfer to a medium bowl and mash until very smooth. Weigh out 250g of the mashed sweet potato and keep the rest in a sealed container in the fridge for another recipe.
3. Reduce the oven temperature to 160c (fan) then grease and line a 22×12 cm loaf tin with the vegan butter and baking parchment. Set aside.
4. In a medium bowl, whisk together the flour, sea salt, baking powder, bicarbonate of soda, ground cinnamon and ground ginger. Set aside. 
5. In the cup of a high-speed blender, place the remaining ingredients. Blend until smooth then whisk into the sweet potato mash until smooth. Fold in the dry ingredients until just combined and then transfer to the lined loaf tin. 
6. Place in the oven and bake for 1 hour and 30 minutes. Remove form the oven and test with a skewer – it should come out clean. Leave to cool on a cooling rack until cool enough to handle then remove from the tin and leave to cool completely. 
   1. Pour the coconut milk into a small saucepan and add the icing sugar. Place over a low heat. Heat the coconut milk until it’s just about to boil (you should see small bubbles appearing at the side of the pan) but do not allow it to boil fully. Stir the coconut milk with a spatula as it heats.
   2. Once hot, remove from the heat and add the chocolate. Cover with a lid and leave to rest for 15 minutes.
   3. Once 15 minutes is up, remove the lid and whisk well until smooth. Set aside to cool for 5 minutes. Meanwhile, place the cooled cake on a wire cooling rack sat over a medium bowl. 
   4. Once the ganache has cooled and thickened slightly but is still glossy and pourable, pour it all over the cake, catching any excess in the bowl below. The ganache should cover and coat the cake, but if you miss a bit, use the excess ganache in the bowl below to repeat the process. 
   5. Cover the cake and place in the fridge to chill until the ganache is set, then slice and serve.

To Make the Chocolate Ganache

1. Pour the coconut milk into a small saucepan and add the icing sugar. Place over a low heat. Heat the coconut milk until it’s just about to boil (you should see small bubbles appearing at the side of the pan) but do not allow it to boil fully. Stir the coconut milk with a spatula as it heats.
2. Once hot, remove from the heat and add the chocolate. Cover with a lid and leave to rest for 15 minutes.
3. Once 15 minutes is up, remove the lid and whisk well until smooth. Set aside to cool for 5 minutes. Meanwhile, place the cooled cake on a wire cooling rack sat over a medium bowl. 
4. Once the ganache has cooled and thickened slightly but is still glossy and pourable, pour it all over the cake, catching any excess in the bowl below. The ganache should cover and coat the cake, but if you miss a bit, use the excess ganache in the bowl below to repeat the process. 
5. Cover the cake and place in the fridge to chill until the ganache is set, then slice and serve.