Preheat the oven to 400 degrees.
Drain the cashews from the soaking water. In a blender, combine the cashews, milk, lemon juice, mustard, salt, pepper and garlic powder. Blend until very smooth.
After you have thawed the spinach, make sure you get as much water as you can out of it by squeezing it in a dish towel. Add the spinach and artichokes to the blender, and only pulse a few times. You want to keep some of the chunky texture of the artichokes, so don't blend it until smooth.
Transfer the mixture to a baking dish that is sprayed with non-stick spray. Sprinkle the vegan parmesan on top, and bake for 25 minutes. Then for the last 5 minutes, turn on the broiler to brown the top. (keep an eye on it when broiling because it can burn fast)
Serve warm with gluten-free bread, crackers, or veggies.