Pumpkins and winter squashes like butternut, acorn, and kabocha will keep for months when stored in a cool, dry place, but sometimes it's helpful to extend their shelf life even more. And the best way to do it is by freezing.
Regardless of the variety, and whether you're working with raw or cooked winter squash, here are the two best methods for preserving it in the freezer.
Peel and Freeze Cubes of Raw Butternut Squash
The best way to freeze raw butternut and other varieties of winter squash is in one-inch cubes, after first peeling it and removing the seeds.
Peel and cut the squash into one-inch chunks. Spread the pieces in a single layer on a parchment or wax paper-lined baking sheet and place in the freezer. When completely frozen, transfer the squash to a freezer-safe bag or container with about 1/2 inch headspace to allow for food expansion. The squash can be roasted straight from the freezer (no thawing necessary!), or tossed directly into soups, stews, and chili.
Roast it: How To Roast Frozen Butternut Squash
Recipes to Use Thawed Butternut Squash Cubes
Portion and Freeze Cooked Butternut Squash
When cooked, the best way to freeze winter squash is as a purée, which holds up well once thawed. And the best method is to portion the puréed squash, then freeze for later.
Purées can be frozen in ice cube trays, muffin tins, and in small portions (about 1/2 cup) on a parchment or wax paper-lined baking sheet. Once frozen, the purée can be transferred and stored in a resealable freezer bag for up to three months.
Defrost the purée and reheat in the microwave or on the stovetop to be used for sauces, dips, lasagna, and muffins (try an equal amount in place of pumpkin purée), or add it directly to simmering pots of soups, stews, and chili.