Heat oven: Preheat your oven to 350°F (175°C).
In a medium saucepan, bring the vegetable broth to a boil. Add the trimmed and cut green beans and cook them for about 5 minutes, or until they become tender-crisp. Drain the beans and set them aside.
In the same saucepan, melt the vegan butter over medium heat. Stir in the all-purpose flour and cook for 1-2 minutes to make a roux.
Gradually pour in the plant-based milk while whisking continuously to avoid lumps. Cook the mixture until it thickens and becomes smooth.
Season the homemade cream of mushroom soup sauce with onion powder, garlic powder, black pepper, and salt. Adjust the seasonings to suit your taste preferences.
If you’re adding sliced mushrooms, sauté them in a separate pan with a little oil until they are tender, then mix them into the sauce.
Add the cooked green beans to the sauce and stir until they are evenly coated.
Transfer the green bean mixture to a greased casserole dish.
Sprinkle the crispy fried onions on top of the casserole, creating an even layer.
Bake the green bean casserole in the preheated oven for about 20-25 minutes or until it is heated through, and the top is golden and crispy.
Remove the casserole from the oven and let it cool slightly before serving.
Enjoy your delicious and comforting green bean casserole Durkee recipe, perfect for gatherings and holiday dinners!