Creating Vegan Green Bean Casserole is simple if you follow these steps:

1. Preheat the Oven: Preheat your oven to 350°F (175°C).
2. Prepare the Green Beans: Blanch the green beans in boiling water for about 3-4 minutes, then drain and set aside.
3. Sauté Vegetables: In a large skillet, heat a tablespoon of olive oil over medium heat. Add the diced onion and sliced mushrooms, cooking until softened (about 5-7 minutes).
4. Add Garlic: Stir in the minced garlic and cook for an additional minute until fragrant.
5. Create the Sauce: Pour in the vegetable broth and plant-based milk. Add nutritional yeast, soy sauce, onion powder, garlic powder, black pepper, and salt. Stir well to combine.
6. Thicken the Sauce: Mix the cornstarch with water to create a slurry, then add it to the skillet. Stir continuously until the mixture thickens, about 2-3 minutes.
7. Combine Ingredients: Add the blanched green beans to the skillet and stir until they are well coated with the sauce.
8. Transfer to Baking Dish: Pour the mixture into a greased 9×13-inch baking dish, spreading it evenly.
9. Add Topping: Sprinkle the crispy fried onions on top of the casserole.
10. Bake: Place the baking dish in the preheated oven and bake for 30-40 minutes, or until the top is golden brown and crispy.
11. Cool and Serve: Remove from the oven and allow the casserole to cool for 10-15 minutes before serving.

These steps will guide you in creating this incredible Vegan Green Bean Casserole effortlessly.