1. I wanted to take bread to a pot luck a couple of weeks back
2. I had a plethora of squash (that's the understatement of the year)
3. At least one vegan would be attending, and, as a sometime/semi vegetarian, I am highly sympathetic to the plight of "oh, crap, the only thing I can eat in this entire spread of food is the thing I brought myself!"
I decided braided loaves would be nice for presentation, but of course I didn't want to use eggs, butter or milk. Beard On Bread has a recipe for sweet potato bread that my sister and I have riffed on for years, often subbing in squash for the sweet potato. And for what it's worth: I don't think it matters at all what kind of winter squash (or pumpkin) you use.
Preparing the squash: I usually halve the squash, scoop out the seeds, oil the cut surfaces lightly, and then bake, face down, at 350 or 375 till soft. Lately, I've been putting a cup or so of water in the roasting pan as well. I think it cooks better when there's some moisture in there.
Next, I let the squash cool, then scoop out the flesh and run it through the food mill. I know people who skip this step and use the processor instead, but I wouldn't just mash it by hand. Strings or lumps will mar the quality of your bread!
If your squash is particularly watery, you may need to adjust the quantity of water in the bread. (For pies, I generally cook the puree down in a skillet; for bread, it doesn't much matter because you can just add less liquid.)
To make the breads (this recipe makes two loaves):
6 cups flour
1 1/3 cup squash
1 scant T yeast (I use instant)
1 T salt
1/3 cup oil
3 T maple syrup
1 1/3 cup water
Mix all ingredients till you have a nice, elastic dough. Knead then shape into a round; cover the bowl and let rise till doubled.
Divide the dough into six equal pieces (I use a scale but you could just eyeball it). Braid into two loaves and cover and let rise again, about half the time you let it rise the first time. Brush with water and sprinkle with poppy seeds, if you like.
Bake at 375 for 45 minutes to an hour.
(Note: the first time I made this I did an overnight [about 12 hours] rise on the counter and only used 1/4 tsp of yeast. Given how cold my kitchen is overnight in November, I probably should have used a touch more yeast, but it did okay.)
I liked this bread so much (and I still had the plethora of squash) that I used it for my Thanksgiving stuffing.