I smoked a turkey and made gravy using this how-to recipe yesterday on my XL Big Green Egg:

http://amazingribs.com/recipes/chick...ed_turkey.html

It was the single best turkey and gravy I have ever made or tasted.

EVER.

And every other person at the table agreed.

It can be done in an oven, as well...but there may be some skill involved with getting a drip pan under a spatchcocked 18lb bird.