Preheat the oven to 160ºC (340ºF). Lightly grease a 25-cm round cake pan and line the base with baking paper.
Whisk the eggs, sugar and vanilla together, until pale and thick. In a separate bowl, mix all dry ingredients; sift in the flour, baking soda, baking powder, salt and cocoa, and stir to combine.
Combine the egg and sugar cream to dry ingredients, and whisk the vegetable oil, stirring well until the mixture are well incorporated. Stir in the buttermilk and boiling water. Mix thorougly untill well blended.
Pour into the prepared pan, and bake in the oven for 50 minutes, or until the center is firm to touch and a skewer comes out clean when tested. Leave the cake to cool in the pan for 20 minutes before turning out into a rack to cool completely. Cover with any chocolate frosting you desired.
Serve, share... and enjoy!
