Preheat the oven to 160°C (fan) and line a 2lb loaf tin.
In a large bowl, whisk together the flour, baking powder and cinnamon.
In a separate bowl, whisk together the buttermilk, brown sugar, maple syrup, yoghurt, sunflower oil and vanilla paste until smooth.
Add the wet mixture to the dry ingredients and fold gently until just combined. Then add the chopped pecans.
Pour the mixture into the tin and bake for 50–60 minutes, or until a skewer inserted into the center of the cake comes out clean. Allow the cake to cool completely.
For the maple icing, beat the butter and icing sugar until soft and smooth. Add the maple syrup to loosen the mixture.
Pipe or drizzle the icing over the cake after it has cooled, and finish with some chopped pecan pieces. You can add maple flakes as a decoration too, if you like.