A wonderfully comforting dish, this serves two. Feel free to double or even triple the recipe: you’ll want extra helpings!

For the Mushroom Sauce:

½ yellow onion, roughly chopped
300g white mushrooms, roughly chopped
2 cups vegetable broth
1 cup soy (or other all-plant) milk
½ tsp salt, or to taste
¼ tsp white pepper
½ tsp dried sage
½ tsp dried rosemary
½ tsp dried thyme
¼ cup nutritional yeast
2 tbsp cornflour

For the Casserole: 
400g frozen green beans

For the Topping: 
4 onions, cut into strings and fried (we air fried ours, which takes much longer than deep frying; instructions below).

Directions
1. Preheat oven to 170C.
2. Make the sauce by sautéing the onions and mushrooms over a medium low heat until the mushrooms start to release their liquid. Don’t allow to take on much colour. Add the rest of the ingredients apart from the cornflour, and simmer for about 20 minutes. 
3. Meanwhile, cook the green beans according to package directions, and refresh in cold water to stop them cooking. Drain. 
4. When the sauce is ready, blend and return to the pot. Mix the cornflour with enough water to get a smooth paste. Add to the sauce and simmer to thicken. 
5. Transfer the beans to an ovenproof dish and pour over the sauce. Bake for 20 minutes. 
6. Top with the crispy onion strings and serve. 

To make the onion strings: 
1. Slice the onions on a mandoline. 
2. Transfer to an air-fryer basket and fry for 5 minutes at 120C. Toss and fry for another 5 minutes.
3. Lower the heat to 100C, and fry the onions for another 50 minutes or so, tossing often and checking that they don’t burn.