Soak the cashews in boiling water for 5 minutes. Drain and set aside.
Boil the potatoes and sweet potatoes in salted water until tender, about 12 minutes, then drain.
To make the vegan cheese sauce, combine the cooked potatoes with the garlic, cashews, apple cider vinegar, nutritional yeast, onion powder, salt, olive oil, and water in a blender or food processor and blend until creamy.
Boil the elbow macaroni until al dente, reserving ½ cup of pasta cooking water.
Combine the macaroni with the vegan cheese sauce, mixing until evenly coated and adjusting the consistency of the sauce with the reserved pasta cooking water as needed. Enjoy!