Preheat the oven to 170C or 150C fan and line a 20cm square baking tin. Or you can use these enamel bowls from Falconware. I had about 8 leftover from the cafe and this mixture will easily fill those.
Blitz the oats in a high speed blender or food processor until you have a thick breadcrumbs consistency.
Add them to a bowl along with the flour, bicarbonate of soda, ground ginger.
Grate in the jaggery. You can use soft brown or dark muscovado sugar but I had a load of jaggery to use up and find that it gives an earthier flavour.
Mix well to combine and set aside.
Break the eggs into a jug. Add the milk and then whisk together and set aside.
Weigh the butter, syrup and treacle into a small saucepan and heat on a gentle heat until it's all melted.
Pour the melted mixture into the four and jaggery mixture and mix well. You don't need to use a whisk. A wooden spoon is fine.
Now pour in the egg and milk mixture and mix again until it is all combined.
Pour into the baking tin and bake for 45 minutes. It will feel soft and when you pop a cocktail stick in, it will not come out clean. That's good. You want this a little moist.
Note - if you are using the smaller enamel bowls, this won't take 45 minutes. About 20-25 minutes is more likely.
While it is still warm in the baking tin, spoon over the ginger syrup.
Once your ready to eat, mound over some marshmallows and then blow torch them a little or pop under the grill to burn and soften a little at the edges.