This is something I have a lot of experience with, due to a longstanding butternut squash and pumpkin addiction. I freeze a lot
of butternut and pumpkin for use in pie and soups.
First, Deb is correct that winter squash will keep well in a cool, dry place. The key here is both
cool and dry. The ideal temperature is somewhere in the 40s to lower 50s. If your basement stays dry all winter and it's not heated, that may work as a sort of "root cellar". Because I have a big ol' boiler in my small basement, it heats up into the 70s so I store my winter squash in my "root attic"
My attic stays dry and in the low 50s all winter, and I kept a lot of butternut squash there through March this winter (by April I'd eaten it all).
But I realize you are asking about freezing methods. I freeze it both in 1" chunks for use in squash soups (yum!) and also in puree for use in pies or super-quick soups (another yum!). I find that a FoodSaver or other brand vacuum sealer is really valuable for freezing squash -- I've never had freezer burn or even much frost on the squash, and have I literally kept frozen puree for a year using my FoodSaver.
If you don't vacuum seal the squash, I'd put it in a double layer of freezer bags and squeeze out as much air as possible before sealing -- it won't last as long and you might get some frost, but should still last 3 or 4 months.
Freezing chunks is self-explanatory - just peel, gut the strings (roast the seeds if you like), and cut it up.
For puree, this is what I do - I admit, it's kind of complicated, so I tend to make an afternoon of it and do a large amount of squash at once.
1. Peel and cut the squash in half.
2. Roast the squash halves in the oven, cut size down in a pan with 1/4" in of water to prevent scorching, at 350 to 400 degrees until a fork pokes through with no resistance. You can also microwave or cut it up in chunks and steam it -- but roasting will concentrate the sugars wonderfully.
3. Let the roasted squash cool and then peel it with your fingers -- peels will slip right off it you've roasted long enough.
4. Puree the cooked squash in a food processor or food mill. A blender doesn't really work too well. A stand mixer at progressively higher speeds can work OK if you don't mind some lumps and a few strings. I puree the heck out of it in my food processor until there are no stringy bits left.
5. IMPORTANT STEP: You want to drain your puree to get rid of excess water. If you make a pie with fresh puree, this will keep your pie from being soupy; if you're freezing puree it will freeze better with fewer ice crystals. I like to line a colander with a bunch of overlapping coffee filters, spoon in the puree, set the colander in a large bowl, cover the whole thing w/ plastic wrap, and drain overnight in the fridge. But even a few hours of draining at room temperature will help, although it's safer to use the fridge.
6. Measure the puree in 2-cup amounts (or whatever you want for future recipes). If you're not using a FoodSaver type device, you can put in freezer bags now. If you are going to vacuum seal, it's helpful to freeze the puree a few hours in a flexible plastic container (I use the shallow, rectangular Glad food storage containers from the grocery) to firm it up, then pop out the frozen blocks of puree and vacuum seal individual blocks for long term storage.
Believe it or not, once you get some practice at this method, it really doesn't take that much actual time -- a lot of it is waiting when you can do other things. Sort of like baking bread.
Eric, the cucurbit fiend