Here, I add some extra chopped chocolate pieces to the mix right at the end,
but if you want to reduce the fat levels even further, stir in the same weight
of dried blueberries or sour cherries instead.
100g unsalted butter
200g dark chocolate, chopped
200g baked sweet potato, flesh scooped out
125g brown sugar (any sort)
2 medium eggs
2 tsp vanilla extract
100g plain flour
tsp baking powder
100g chopped pecans
Line an 18cm square tray-bake tin (or similar) with nonstick paper or foil, and
heat the oven to 180C (160C fan-assisted)/350F/gas mark 4.
Melt the butter in a saucepan, then add 125g of the chocolate and stir until
that's melted, too. In a bowl, beat the sweet potato flesh with the brown sugar
until almost smooth, then mix in the butter and chocolate. Add the eggs and
vanilla, beat until thick, then stir in the flour and baking powder until
evenly combined. Fold in the pecans and remaining chocolate, then spoon into
the tin, smooth the top and bake for about 20-25 minutes, until barely cooked
but still a bit soft under the crust. Leave to cool completely in the tin
before slicing.