Cut the acorn squashes in half. Sprinkle the baking soda and salt on the cut surfaces.

Put 1/2 a cup of water in the Instant Pot, fit the rack in it, and stack the squash on top. Close the lid, close the valve, and cook on high pressure for 24 minutes. Do quick release.

When squash is cool enough to handle, scoop it out into a bowl, mash it, and add the rest of the ingredients.