Pre-heat oven to 180⁰C.
Grease and line a 17.5cm/7” round shallow cake tin.
Melt the butter and sugar in a sauce pan over a low heat until melted.
Stir in the mashed banana.
Add the spelt porridge flakes and mix in thoroughly.
Tip the mixture into the cake tin and pat down and even surface with the back of a spoon.
Bake in the centre of the oven for 20 minutes or until firm to the touch and golden.
Whilst still warm mark into 8 sections and allow to cool in tin.
Once cool remove from tin and place on a wire rack.
Meanwhile melt the 50g of dark chocolate over a bowl of barely simmering water.
Pour chocolate over the middle of the cooled flapjack and spread in a circular motion with the back of a spoon.
Allow to cool before cutting up and serving.