Place a saucepan on medium high heat and add a cup of water.
In a small jug mix the cocoa powder with the remaining half-cup of water to a smooth paste.
Add the sugar to the water in the saucepan then slowly stir in the cocoa/water mix until it is smoothly combined.
Bring to the boil, switch off the heat, and allow to stand on the still warm plate while you prepare your pudding batter.
Preheat oven to 350 degrees C (180 degrees F).
Grease a baking dish with butter or coconut oil.
In a large bowl mix the flour, baking powder, salt, cocoa powder and sugar.
In a jug mix the milk and melted butter, the egg and the vanilla essence.
Mix the wet ingredients with the dry ingredients to create a rather stiff batter.
Spread it into the baking dish – it may not touch the sides but this is fine – it will expand as it cooks.
Gently pour the sauce over the batter – it may look something like a volcanic landscape but it will all work out.
Place the baking dish in the oven for 30 minutes or so – the top should bounce back when touched. Do not let it overcook or there will be less sauce as the batter will absorb it.
When you remove it from the oven do so carefully without tipping the dish, as the pudding will be floating on its sauce underneath.
Make sure you serve the pudding within minutes of taking it from the oven so you have the contrast of the hot pudding and gooey chocolate sauce contrasted with the coldness of the ice cream.