i am making a Guinness cake for my new hubby as his grooms cake. the wedding is on St. Patrick's day so i felt this is going to be so fun for everyone. problem is i need to use square pans in order to make up at least a half-sheet cake. the recipe says that i should use spring form pans, will they be ok if i use regular 9X13 pans to make up a half sheet? any tips on making this a success?