Does anyone know what size cake box to buy for an 11 x 15 sheet cake?....and if so, where can I buy them online?
ULINE sells boxes for 1/4 and 1/2 sheet cakes - just check the sizing to see which one fits: http://www.uline.com/BL_5613/Cake-and-Bakery-Boxes?keywords=cake%20boxes
Otherwise, check this out - it seems to answer your questions: http://www.makeacakehouston.com/documents/boxes_and_boards.html
Thankyou for your help.
Bulk Barn carries cake boards and boxes large enough for sheet cakes. Bonus, they're on sale 15% off this week (at least in Atlantic Canada)