I asked Chriss for her recipe a while back but haven't had it so in the meantime I thought I'd trawl the internet for something that might taste roughly similar (i.e. something with treacle). Here's the one I found and tried today:
Makes ~6/8, ~30 minutes.
115g/4oz caster sugar
2dsp black treacle
1dsp plain flour
Grease and lightly flour a baking tray, preheat the oven to 180C/350F/Gas 4. Melt together the margarine and treacle over a low heat before adding dry ingredients. Mix well before turning off heat and pressing into baking tray. Bake ~20 minutes and cut into slices whilst still warm. Remove from tray once cooled.
(recipe adapted from this post on Farmhouse Recipes)