Preheat the oven to 170°C/ gas mark 3. Lightly butter a medium sized baking dish. Melt the butter and leave aside.
Use an electric mixer with a paddle attachment to mix the eggs and sugar on a medium speed for 5-10 minutes, until the mixture is thick in consistency and pale yellow in colour. Meanwhile, sift the cocoa powder and flour together in a separate bowl and set aside.
When the egg and sugar mixture is light and fluffy, reduce the speed and add the vanilla seeds, cocoa powder and flour mixture. When the mixture is combined, with the mixer still on, pour in the cooled butter and mix again until combined.
Pour the mixture into the prepared dish and place it in a baking tray. Pour hot water into the baking tray to come halfway up the side of the dish and bake for an hour. The centre of this pudding should be deliciously gooey so don’t over bake!
Allow to cool and serve with vanilla ice cream.