Preheat your oven to 180c and line a loaf tin with baking paper.
Mix the milk and apple cider vinegar together and set aside.
In a large mixing bowl, cream together the butter and coconut sugar until light and fluffy.
Beat in the eggs and sweet potato until well combined.
Gradually add in the flour and milk whilst stirring until you're left with a smooth batter.
Fold through the baking powder, bicarb, cocoa powder, salt, cinnamon and finally the chocolate chunks.
Pour this into your loaf tin and bake in the oven for around 45 minutes, then allow to cool thouroughly.
For the frosting, gently melt the chocolate and coconut oil together. Mix in the peanut butter, cocoa powder and finally coconut milk.
Spread this over your cooled cake and decorate with fruit or other toppings of choice.