My Mum use to cook this all the time for me when I was little but then the recipe got lost for years and years. I discovered it recently while clearing out so made some myself and it was just as good as I remember.
Mix together all the dry ingredients (minus the salt) in a big bowl.
Whisk together the water, oil, vanilla and salt in a separate bowl.
Mix together the oil mixture with the dry ingredients.
Pour in to a giant roasting tin.
Bake in the oven for 20-30 minutes at 190'C.
I love to eat a bowl with milk while it's still hot but you can leave it to cool and pour in to an air-tight jar for the next day.