In bowl add flour and baking powder and mix cocoa powder and mix well
In other bowl add sugar and butter. mix well like cream
Now add egg and vanilla extract and mix well
Now mix both mixture without lumps
Now add butter milk and color and mix well
In bowl add vinegar and baking soda. it rise foam mix with cake mixture
Now batter is ready and now transfer to baking tin
Pre heat the oven for 10 mins bake for 180 degree for 40 mins
Beat heavy cream with icing sugar, vanilla essence
Now cut the cake in two layer and cut top layer little for decorating
Apply apply cream and make crumb coat
Refrigerate for 30 mins
Now apply again cream and sprinkle crumbled cake on top
Now decorate as your wish with cream and finish it . now its ready .