Use a sharp knife to carefully cut off both ends of the butternut squash.
Pierce the skin of the squash in several places with a fork or knife to allow steam to escape during cooking.
Place the whole butternut squash in a microwave-safe dish or on a microwave-safe plate.
Microwave the squash on high power for about 5 minutes to soften the skin.
Remove the squash from the microwave and allow it to cool slightly for easier handling.
Use a sharp knife to carefully cut the butternut squash in half lengthwise.
Scoop out the seeds and stringy fibers from the center of each half using a spoon.
Place the two halves of the squash, cut side down, in a microwave-safe dish.
Add a little water to the dish, about 1/4 cup, to create steam.
Microwave the squash halves on high power for about 8-10 minutes, or until the flesh is tender and easily pierced with a fork. Cooking times may vary depending on the size and thickness of the squash.
Once cooked, carefully remove the butternut squash from the microwave and allow it to cool slightly before handling.
Use a spoon to scoop out the cooked flesh from the skin and transfer it to a bowl.
Mash the cooked butternut squash with a potato masher or fork until you achieve a smooth consistency.
Proceed with the mashed potato squash recipe, combining the mashed butternut squash with the mashed potatoes and other ingredients as specified.