Dense, heavy cake!! HELP!!!!

[tealbox]

Hi all, I just registered here and I am pretty new to the cake business but I am trying to find the best recipes and amazing cupcakes. I had my first wedding cake consultation and sampling yesterday (thank god it was a family friend) The filling, home made fondant and butter cream were perfect. The cake on the other hand was a disaster in my eyes, even though they said it was good. It was very heavy and dense. I had extra batter and made some cupcakes, the cupcakes came out fluffy and amazing, What happened? I used a 6" round pan. Could it be that I filled the pan too much would that cause the cake to be heavy and not be fluffy?

Any answers would be greatly appreciated,

Thanks!!!

[cakewhiz]

I am not sure what happened :S
But, have you used this recipe before for cakes? Maybe this batter is more suitable for cupcakes rather than cakes. For example, i never use my pound cake batter for cupcakes....it just does not have that "cupcakey" feel...