First, cook the butternut squash by following one of the 3 methods below: oven, stove or Instant Pot.

To Cook Butternut Squash in the Oven

• Halved Squash: Preheat oven to 375° F. Line a rimmed baking sheet with parchment paper. Slice a small amount off of the stem and base ends of the squash and then cut the squash in half lengthwise. Scoop out the seeds. Place the squash halves, cut side down, on the prepared baking sheet. Roast in the oven for 35-45 minutes, until soft when pierced with a fork. Let cool slightly and then scoop the squash out of the skin.

  Cubed Squash: Bake 1-inch squash cubes at 400° on a parchment paper lined baking sheet for 30-35 minutes, tossing halfway through the cook time, until soft.

To Steam Butternut Squash on the Stove

• Put an inch or two of water in the bottom of a pot or saucepan. Add a steamer basket to the pot.
• Bring to a boil over high heat. Once boiling, add 1-inch squash cubes to the steamer basket and cover the pot. Reduce heat to medium high and cook for 7-9 minutes, until tender.

To Cook Butternut Squash in the Instant Pot

• Quartered Butternut Squash: Cut off the stem end of the squash. Cut the squash in half crosswise, at the point where the squash widens. Stand each squash half on its flat end, cut in half, and then scoop out the seeds. Put 1 cup water in the Instant Pot (1½ cups for 8 quart pot). Put the metal trivet in the pot and place the four squash pieces on the trivet. Pressure cook at high pressure for 10 minutes, followed by a 5 minute natural release. Quick release the remaining pressure. Let cool slightly and then scoop squash out of the skin.

  Cubed Squash: Put 1 cup of water in the bottom of the Instant Pot (1½ cups for 8 quart pot). Add a steamer basket to the pot. Put 1-inch squash cubes in the steamer basket. Cook at high pressure for 3 minutes. Quick release the pressure.

To Make the Butternut Mac and Cheese

• Place the squash in a blender or food processor and add ½ cup of the vegetable broth. Puree until very smooth. Set aside.
• Bring a large pot of water to a boil. Cook the pasta according to the package directions. Drain and return pasta to the empty pot.
• In a medium saucepan, melt the butter over medium heat. Add the garlic and chopped sage and cook for 1 minute, stirring.
• Whisk in the flour, nutmeg, salt and pepper. Cook for 30 seconds, stirring constantly.
• Whisk in the remaining ½ cup of broth and the milk. Cook, stirring often, until thickened, about 3 minutes.
• Remove from the heat and stir in the cheese. Then stir in the pureed squash mixture.
• Stir the butternut cheese sauce into the pasta.
• If the mac and cheese is not hot enough (this may be the case if the squash was cooled), warm it over low heat on the stove, stirring often, until hot. Serve.