As is usual with deciding on a Materials and Method, I looked up different recipes and implementations before deciding on what I would use myself. I followed Nigella's for quantity. The ingredients are: Pitted dates; butter; eggs; flour; brown sugar; and black treacle (see below). The pudding texture should be moist and crumbly but still holding together.

If you do not have black treacle handy, you can do what I did which was to use molasses sugar dissolved in a bit of water to and come up with what is essentially treacle.