I'm nearly done reading it for the first time. If memory serves, Bilbo attempts to be a sneaky burglar for the first time with the trolls, but accomplishes nothing besides getting himself captured, and the dwarves bagged when they tried saving him. While he's laying in a bush, Gandalf does the voice trick, and reveals himself with the "the dawn will take you all!"

In the movie, Bilbo wastes their time by making pointless cooking suggestions, until the sun comes up just enough for Gandalf to break the rock and do the "dawn take you all" bit. Thorin complains to Gandalf that Bilbo got them captured in the first place, but Gandalf commends Bilbo for having "the nous to beg for time".

So the movie actually moves the accomplishment from Gandalf to Bilbo