Birthday cake, please help!

[whateverfloatsyourboat]

Got a number 6 cake tin for ds's birthday - he wants a chocolate cake and I'm going to cover it in a white chocolate ganache. I was going to do Nigella's buttermilk birthday cake - can I just add cocoa to that to make it a chocolate one, or would it taste funny? And if so - how much cocoa powder?! (Cake mix is 3 eggs, 250g flour, 200g sugar).

Or can I just make a basic chocolate sponge? Would that work in the tin? And bear the weight of the icing?!

Just add 200g of flour and 50g of the cocoa powder. you may need a splash of milk as the cocoa powder is drier than flour.

Or the chocolate sponge would be fine.

Thank you! (You do mean only use 200g of flour and add 50g cocoa, right?)

Sorry, boss came in mid typing

Hope it goes ok.

....back to work.......

Yep, instead of :3 eggs, 250g flour, 200g sugar).
do 3 eggs, 200 flour, 50 cocoa, 200 sugar and maybe a splash of milk.

Oops, thanks again! Off to make it now.