Return the pasta to the large pot. Add the oat milk, pasta water, dijon mustard, vegan cheese, salt, pepper, garlic powder, onion powder and nutritional yeast. Stir on low heat until everything is melted and mixed together and the cheese sauce thickens up.
½ teaspoon salt, 2 tablespoons vegan butter, 1 cup unsweetened extra creamy oat milk, 2 cups vegan cheese, 1 teaspoon garlic powder, 1 teaspoon onion powder, ¼ cup nutritional yeast, 1 tablespoon dijon mustard