Add the macaroni, olive oil, and water to the Instant Pot.
Place a trivet on top of the pasta and set a cake pan over the trivet.
Add the cashews, chopped potatoes, carrots, garlic, vegan butter, and 1/4 cup of water to the cake pan. Cover with a foil.
Cover the Instant Pot with its lid and make sure the vent is closed.
Cook at High Pressure for 4 minutes. Once the cook time is finished, immediately do a quick release.
Remove the cake pan from the Instant Pot and pour its contents into the blender.
Remove the trivet and stir the pasta.
Add the remaining sauce ingredients to the blender and blend on High for 30 seconds or until smooth.
Pour the sauce mixture back into the Instant Pot and mix everything well. The sauce will initially look thin, but it'll thicken as you stir it with the pasta for a few minutes.