Place 1 cup unsalted shelled pumpkin seeds in a bowl and add enough cold water to cover.
Let the seeds soak at room temperature for 6-8 hours.
Drain and discard the soaking liquid, then transfer the pumpkin seeds to a high-powered blender.
Add 1 cup cold water, 1/2 cup nutritional yeast, 2 tablespoons tapioca starch, 2 tablespoons lemon juice, 1 teaspoon salt, 1/4 teaspoon garlic powder, and 1/4 teaspoon onion powder to the blender.
Blend until smooth and creamy.
Pour the mixture into a pot on the stove set to medium heat.
Whisk frequently while cooking for 3-6 minutes or until it becomes thick and stretchy, then immediately remove from the heat.
Use right away in dishes such as grilled cheese, pizza, mac and cheese, or lasagna.
Or transfer the mixture to a container and refrigerate for at least 2 hours, then use as a cream cheese-style spread.