Sorry to chime in here a couple of years late, but I find it curious that a community of people that is so dedicated to purism in preparation and brewing from scratch would settle for canned pumpkin and blended 'pumpkin pie spice'. Make your own pumpkin pie spice and roast your own pumpkin, hubbard blue, or acorn squash and truly take control of your beer!!!
Any way, I'm about to embark on this recipe, but using a giant 22lb Hubbard Blue Squash. It has been in the oven (peeled, deseeded chunks resting in a covered pan with an inch of water at 450 F) for 45 minutes so far. Will probably push it to 1hr or 1.5 and then blend it and return to the oven for 30 minutes for carmelization.
Here is my pumpkin spice blend:
10 cardamom pods
.5 nutmeg, grated
2 cinnamon sticks
tsp of mace