Butternut Squash

Concept
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What happens if you make a beer where you use pumkin as a fermentable and use as much of it as possible? The plan is to try to isolate the pumpkin flavor specifically. It will be roasted for 1 hour at 375F, but I will forego sprinkling with brown sugar. I want only the pumpkin sugars to be contributing to the mash. Then, I'll have to blend the pumpkin so that as much of the sugar as possible is accessible to the enzymes.

PPG of Pumpkin
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I'm using the wild ass guess of 8 as a starting point from this post:
https://www.homebrewtalk.com/threads/pumpkin-specific-gravity.196466/

The big question on this is will it finish fermenting? If I use the minimum recommended diastic power of the mash, can I get the full conversion? Will it just take longer? I've lengthened the mash to 120 minutes to see if it affects the conversion of whatever starches may be present in the pumpkin.

Furthermore, if you max out the pumpkin contribution as a fermentable, what on earth will it taste like? Pumpkin juice from Harry Potter? Will it just end up reading as a surprisingly normal beer?

Note on quantity of pumpkin to buy
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2 sugar pie pumpkins reduced down to 19oz of roasted pumpkin when I did burninating the pumpkinside. This requires 56 oz of roasted pumpkin. That adds up to roughly 6 pumpkins, I believe.

EDIT:
They didn't have any more sugar pie pumpkins because it's the day after thanksgiving. So I am switching to acorn squash. Though Kate suggested that Butternut might have been a better choice.

EDIT2:
I screwed up roasting the acorn squash. I left them in the oven when we left for a party. Hours later we came home and the whole house smelled pungently of squash. I discovered I had never taken them out and the oven was still on. I composted the desiccated husks, and felt suitably shitty about myself about the whole thing.

It seems like roasting will cook it down and reduce the volume by about half. So for 3.5 lbs of roasted squash, I'll need 7~ lbs of raw squash.