Pour the water into the insert set in a 5-, 6-, or 8-quart Instant Pot. Set a pressure-safe rack or trivet in the insert.
Finely chop half of the mushrooms, then thinly slice the remainder. Transfer them to a large bowl and stir in the green beans, flour, salt, sage, onion powder, garlic powder, and pepper until uniform. Stir in the cream and milk until well combined.
Pour and pack this mixture into a 2 quart, 7-inch-round, high- sided, pressure-safe baking or soufflé dish. Do not cover. Set the dish on the rack and lock the lid on the pot.
Set the Instant Pot for Pressure Cook or Manual and set the pressure to High. The valve must be closed. Set the time for 20 minutes with the Keep Warm setting off.
When the pot has finished cooking, turn it off and let the pressure return to normal naturally, about 15 minutes. Unlatch the lid and open the cooker. Use hot pads or silicone baking mitts to transfer the (hot!) baking dish to a nearby wire rack. Stir in the cheese, then set aside for 5 minutes to let the cheese melt. Stir again before serving warm.
Pour the water into the insert set in a 5-, 6-, or 8-quart Instant Pot. Set a pressure-safe rack or trivet in the insert.
Put the squash, butter, salt, cinnamon, and nutmeg in a 2 quart, 7-inch-round, high-sided, pressure-safe baking or soufflé dish. Cover the dish with aluminum foil and set it on the rack. Lock the lid on the cooker.
Set the Instant Pot for Pressure Cook or Manual and set the pressure to High. The valve must be closed. Set the time for 45 minutes with the Keep Warm setting off.
When the pot has finished cooking, turn it off and let the pressure return to normal naturally, about 15 minutes. Unlatch the lid and open the cooker. Use hot pads or silicone baking mitts to transfer the (hot!) baking dish to a nearby wire rack.
Uncover the baking dish. Use a potato masher or a handheld electric mixer at medium-low speed to mash the butternut squash right in the dish. Check for salt to taste and serve warm.