Cake is limited to JUST being a dessert. Pie is not limited to this as we can clearly see in chicken pot pie, crawfish pie, sheperds pie, minced meat pie, etc..
Pie is a treasure chest of open imigination and delight, while cake is only to complement something else and is a palette for icing or a place holder for candles. If pie would be served at a wedding it would be served at or during the wedding and not after. Cake comes second then, and second now.
The only way you can select cake is that you can never get it off your mind and you may wish to up your dental plan and buy some bigger pants. The only other way you can select cake is that you prefer things that are limited, just sit there, and come in second to everything else, which means by selecting cake you are selecting pie as number one and we thank you.