For The Cake For The Decoration

1. Preheat the oven to 180 degrees Celsius (350 degrees Fahrenheit).
2. Cook sweet potatoes by boiling, steaming or roasting them until very soft and tender.
3. Remove any skins and add them to a food processor with the milk
4. Whizz until completely smooth - you might have to mix it around a few times.
5. Add the blended sweet potato mixture to the same bowl along with the maple syrup, vinegar, salt and ground almonds.
6. Sift in the flour, cocoa powder, baking powder and bicarbonate of soda
7. If using, add the chocolate chips and stir in carefully.
8. Transfer the mixture into a loaf tin lined with greased baking paper (use a one-pound loaf tin).
9. Sprinkle more chocolate chips on top to decorate, if desired.
10. Bake in the oven for approximately 45 minutes until risen and an inserted skewer comes out clean.
11. Once removed from the oven, place on a wire rack and allow to cool completely before slicing.