Sift dry ingredients together. Melt butter and golden syrup together. Let cool. Beat egg into milk, and stir into the butter-golden syrup mixture. Make a well in the dry ingredients, stir in liquid mixture, add banana and chocolate.
The mixture should be rather lumpy, not stirred till it was smooth (or else the Muffins Will Crack apparently.) 2/3 fill muffin pans and bake at 180 C/350 F for 15 minutes.
