it's a tad more complicated when it comes to cookbooks.
a "recipe" as in a listing of ingredients and amounts, is not copyrightable - there are numerous legal cases right up through the Supreme Court which establish that an idea or a fact cannot be copyrighted. of course, lawyers love to debate the definition of things, including the definition of "an idea" and the definition of "a fact." courts have held that a list of ingredients for a dish are a statement of fact.
as MM said tho, the written descriptions of how to make / directions / is considered protected by copyright - any text from every author including the letter you wrote home from summer camp to your parents enjoys full copyright at the instant of its creation - no forms or applications needed.
a cookbook - or a collection of (printed) recipes - can be copyrighted as a "compiled work." however - except in cases of complete verbatim copying - exactly what constitutes a "compiled work" - and what constitutes violation of copyright of a compiled work - is a very sticky wicket.
here's an interesting link to one such case - takes a little slogging to get through it:
http://floridalawfirm.com/meredith.html
but scrolling to the very bottom, the really fascinating part is:
"...The recipes contained in DISCOVER DANNON do not contain even a bare modicum of the creative expression--i.e., the originality--that is the "sine qua non of copyright." ..."
I'm not a lawyer, but reading that, seems the court found even the descriptions of how to put the dish together were not sufficiently original to qualify for "copyright" - much less the ingredients.
which points to Kevin's observation: what is original anymore? short of a "newly invented" ingredient, I suppose folks have combined the existing stuff in many many ways, some combinations taste better than others and 'stick' - some don't.
the day after Reese's Pieces were released, the first guy to put them on an ice cream sundae had an original dish (one could ask, did Reese's already try that in the test kitchen?)
how about chocolate covered oysters on the half-shell...? anybody tried that?