Prepare a container to use as your cheese mold. You may use anything, but somewhat flexible plastic will allow the cheese to come out cleanly once it has cooled.
Mix 1/2 cup water (not included in ingredient list) with the (smaller) calcium packet from the Pomona's Pectin package. Set aside.
Combine the (larger) packet of dry pectin, agar-agar powder, and water in a blender. Measure out your lemon juice and set it aside.
Pour blended mixture into a small saucepan and bring to boil over medium heat, stirring constantly. Turn heat to low and let simmer for about five minutes.
While your water mixture is simmering, Process cashews, nutritional yeast, salt, onion powder, and garlic powder in your blender until they resemble a fine powder (don't overdue it or you'll end up with a savory cashew butter). Pour powder into a bowl and set aside.
Once your boiled water mixture has simmered for about five minutes (enough to dissolve the agar-agar completely), pour it into your blender and IMMEDIATELY add ground cashew powder and lemon juice; blend until completely smooth and creamy (if you have a Blendtec, use the Soup button). Before it thickens, add the calcium/water mixture and process again until it's fully incorporated. Immediately pour the hot cheese into your prepared container.
Refrigerate uncovered for 1-2 hours, then turn the cheese out onto a plate and let set (uncovered) in the fridge for another 4-5 hours. Once fully cooled and set, slice or shred and serve!
NOTE: I know the instructions seem fussy (and you might be considering taking some short cuts)--but there is a good reason for the specific directions! The final mixture is thick and will be thickening quickly as it begins to cool--if you follow directions exactly, you have the best chance of getting all the powder incorporated into the liquid before the mixture is too thick to blend. I started out leaving the powdered mixture in the blender and pouring the boiled water mixture on top, but this resulted in pockets of un-blended powder in my finished block of cashew cheese. It still tasted good, but the texture was a bit lumpy. Beware! ;).