Grease a 6-cup oven-proof dish, or 6 individual ramekins.
For the sauce, mix together cocoa and brown sugar in a jug, pour in hot water, and stir until the sugar dissolves.
For the pudding, sift together flour, cocoa, instant coffee powder, and salt.
Cream butter and sugar until light and gradually beat in the eggs and vanilla.
Add a little flour, then some milk (alternate between the two, keeping a soft consistency), finishing with the flour (don't worry if you don't use up all the milk).
Spoon mixture into a well-greased oven dish and spread evenly. *Optional: sprinkle with 1 T of chopped walnuts.
Spoon sauce over the pudding mixture until you have a layer of sauce, then pour the rest over the back of the spoon.
