Pre heat oven to 180 deg Celsius..line and grease ur pan

Beat butter and sugar until light and fluffy

Add d eggs, one at a tym and vanilla and beat well in between each addition

Sift flour, baking powder

Add the flour to d wet ingredients, this shld be done alternately wit buttermilk..Beginning and ending wit flour

In anoda bowl, mix d cocoa powder wit d hot water. Make a thick paste of d mixture

Remove little less dan half of d butter batter in anoda bowl. This wil b d chocolate batter. Add d cocoa paste to it and mix well

Place the batters in d pan,alternating wit d vanilla and chocolate batter

Swirl the batter lightly using spatula yo create d marbled effect

Place in oven and bake fr 40 mins or until done

Let it cool in pan completely. Enjoy :)