Grain bill

1 pound of Vienna malt, 4L
.5 pounds crystal malt
.5 pounds malted wheat

Other ingredients

6-10 pounds of pumpkin
6 pound light or amber malt extract<\br/> 1 cup of brown sugar (optional)
.5 cup molasses (optional)
1/2 teaspoon vanilla 1/2 to 1 teaspoon pumpkin pie spices

Hop schedule

1 ounce Mt. Hood hops (boiling)
.5 ounces Hallertauer (finishing)

Yeast

Wyeast 1056, American Ale

Directions:

The first thing to say is do not use canned pumpkin! Real pumpkin is the only way to go here, otherwise you'll be dealing with a huge mess. You've been warned.
You'll first need to roast the pumpkin in the oven, similar to cooking squash. This softens the pumpkin and begins breaking it down. Cut the pumpkin into manageable pieces (should be cleaned, of course—old jack-o'lanterns work great), place in a shallow baking pan and add a bit of water to the pan. Roast in a 325°-ish oven for about an hour, or until soft. Or check a cookbook :).
There's two ways you can incorporate the finished pumpkin: a partial mash-style method or simply a soak with the grains as the water heats. For the soak method, simply add the pumpkin and the grains to your pot of water, put it on the heat to boil. When it boils, remove the pumpkin and grains.
For the partial mash, add the pumpkin and grains to hot water (between 150 and 170 degrees Fahrenheit is fine, I believe) and let rest for an hour, then bring to a boil and remove the pumpkin and grains. (Note: I don't have sparging equipment, so this removal is simply via a wire strainer.)
add the malt extract (6 pounds is for dry, you could easily get away with 7 pounds if it's syrup), optional brown sugar and molasses, Mt. Hood hops and boil for 1 hour. After 45 minutes, add the finishing Hallertauer hops. At the very end of the boil, add the vanilla and pumpkin pie spices—these are volatile and adding them to the boil any sooner will essentially nullify their flavor.
Ferment for 1 week, or until primary fermentation settles down, and rack to a secondary for 2 more weeks. The secondary fermentation is not strictly necessary, but I like it for clarification and for letting the flavors mellow. Bottle, priming with ½ cup of corn sugar, and drink after a couple of weeks.
As for the spices, I like a typical mixture of what you'd put into a pumpkin pie: cinnamon, nutmeg, allspice, mace, maybe ginger. I'd avoid buying the generic "Pumpkin Pie Spice" from the store, and mix your own instead—you'll have more control over the outcome. This spice essence is one of the first things you notice when you open a bottle—yum!
I've heard of recipes that don't actually use pumpkin—seems weird to me. I personally think real pumpkin adds a unique flavor and texture to the finished beer that you just can't replicate otherwise.
And, a quick note about the hops. Mt. Hood is a nice spicy, slightly sweet hop (a variant of Hallertauer, actually) that seems to complement this beer well. For finishing, you don't have to stick to Hallertauer; play with it a bit. Cascade might be a nice finish, or if you want to reduce the hop bite, omit the finishing hop altogether.


Thanks to thebrewsite.com for this awesome recipe.
I've already started my batch