In a medium pot, boil sweet potato chunks until fork-tender, about 10 minutes. Boil pasta according to package directions in a large pot of water with 1 teaspoon of salt added until al dente, drain, and return to the pot.
Drain sweet potato chunks, add to a high-speed blender with almond milk, cashews, yeast flakes, garlic, onion powder, tahini, lemon juice, and salt. Process until smooth and creamy. Set aside.
Pour cheese sauce over pasta and stir until fully coated. If needed you can heat pasta while stirring.
You can also transfer pasta to a greased casserole pan and bake in an oven preheated at 400 degrees F. for 15-20 minutes.