Boil water and pour over raw cashews (or sunflower seeds if you're subbing) - let them soak for 10 minutes while you prepare everything else. Drain them once they're done. If you're subbing silken tofu for the cashews, skip this step and just add tofu to the blender with the other cheese sauce ingredients.
Bring a pot of water to boil and cook your shells according to package.
Once your shells have one minute left of cooking, add your frozen veggie of choice to the pasta water with the shells. This will cook the veggies without having to use another pot. Drain when done
While shells are cooking, add coconut milk, cashews (once they've soaked and drained) nutritional yeast, garlic powder, onion powder and salt to a blender (everything but the shredded cheese and pasta basically)
Blend on high until smooth - about 1-2 minutes.
Turn the heat to low on the pan you drained the pasta from and add the cashew mixture and the cup of shredded vegan cheese
Stir and let it thicken a little. About one minute.
If it gets too thick, just add a splash of the coconut milk or water
After about a minute, add the pasta shells to the pan and mix it all together
Add more salt if needed.