I made a cake in the shape of a book. They wanted it half chocolate, half white and a half sheet. So I baked one chocolate 1/2 sheet and one 1/2 white sheet and cut them in half in a way that the cake was half white on one side and chocolate and on the other side. Thing is I can't keep the now two separate cakes from separating. Is there anyway I can "glue" them together? Perhaps royal icing?

I just made my daughter a book for her princess party today, and I baked it exactly the way you did. I didn't use anything to glue the two halves together. I just smooshed them together and iced with buttercream.

Did you "glue" them to the cake board so they wouldn't slide apart?

What do you mean by glue them together? Are you talking about where the center meets or the two layers with fillings. What I do is arrange the cakes side by side and I carve the curve in the center and on the sides until I get the desired shape. Then I torte the two cakes and fill and decorate. Where the two meet in the middle I find a nice piece of long ribbon so that it looks like a fancy bookmark. My customers love the added effect and it covers any seam.

I will try these ideas, you're the best