I am not sure what size pans to use or how to cut to achieve the open book look for my dad's 75th. Of course i have to make today. Any help would be appreciated.
how many servings do you need?
Well, at first I was just gonna say "use the Wilton open book pan."
i only need enough cake for about 15-20
With that many servings, I'd use the wilton book pan. I made a large cake (in my photos) and use two 9x13 cake (1 layer) -- one for each page. You could also cut the 9x13 (1 layer) in half to make a smaller book (if you don't want to buy the pan).
We used 2 square pans and after we put the 2 together, there was a natural dip in the middle that made it look like a book. We really didn't have to do much carving.