A made-from-scratch Vegan Green Bean Casserole with tender green beans baked up in a deliciously creamy mushroom sauce, and topped with crispy, golden, buttery breadcrumbs and tangles of caramelized onions. This really is the ultimate way to eat green beans!
6 oz / 170 g / about 2 heaping cups slicedcremini (brown) mushrooms
4large sprigsfresh thyme
2tablespoonsall purpose flour, plain flour in the UK. Corn starch for gluten-free.
¾ cup / 180 mlvegetable or mushroom broth
½ cup / 120mlsunsweetened non-dairy milk, soy milk works best
½teaspoonsalt, divided - plus more to taste
¼teaspoonfreshly ground black pepper, divided - plus more to taste
Fill a kettle and boil it. Put the trimmed green beans into a large saucepan and pour over the boiling water. Turn the heat to high and wait for them to come to a rolling boil then turn off the heat, drain them in a colander, and immediately rinse them with cold water. Leave in the sink to drain.
In a medium skillet over a MEDIUM heat, add 1 tablespoon of the butter (use a few tablespoons of water to sauté with to keep the recipe oil-free). Once melted and the pan hot, add the onion and cook, stirring frequently for about 15 minutes, until really golden brown. Set aside while you prepare the breadcrumbs.
Break the slices of bread into smaller pieces with your hands and add to the bowl of a food processor along with 1 tablespoon of butter (omit for oil-free), 1 whole clove of garlic and 2 tablespoons of nutritional yeast. Process until fine crumbs. Remove the blade and stir through the sautéed onions. Set aside.
Preheat the oven to 400 °F (200 °C).
Warm the same skillet you cooked the onions in over medium heat and add the last tablespoon of butter or oil (or water for oil-free). Add the sliced mushrooms, the sprigs of thyme and a generous pinch of salt and pepper, then sauté until the mushrooms are golden on both sides.
Add the garlic, cook for a minute more, then turn the heat down to low, remove the thyme sprigs and discard, then add the flour. Stir to coat the mushrooms and continue to cook for 1 minute to remove the raw flour taste.
Pour in about half a cup of the vegetable broth, stirring well as you go to work out any lumps, then add the remaining ¼ cup, stir again then add the non-dairy milk, the remaining 4 tablespoons of nutritional yeast and the remaining salt and pepper. Keep stirring until it is starting to thicken. Turn off the heat, taste and add more seasoning if necessary, then add the green beans to the sauce and stir to coat them.
If you want to bake it right there in the skillet, flatten the beans down as best you can, then spoon over the oniony breadcrumb mixture. Don't compact it. Just leave it loose and rough looking. Or transfer the saucy green beans to an ovenproof dish, then add the breadcrumb topping to the top.
Bake for 25 minutes or until the bread crumbs are golden and the sauce is bubbling around the edges.
Want to make the recipe oil-free? Omit the butter from the breadcrumb topping and use a few drops of water for sauteing. Want to make the recipe gluten-free? Use cornstarch instead of flour in the sauce and gluten-free bread to make the crumb topping. To prep in advance - Prepare the individual components of this recipe in advance, and you can mix the green beans into the mushroomy sauce and have them ready and waiting, covered, in the skillet or any other ovenproof dish. Just leave the filling separate from the oniony breadcrumb topping until you are about to bake it so that it doesn't get soggy. Store the topping in an airtight container, and keep both that and the filling in the fridge until needed. Green beans do tend to spoil pretty quickly, so I wouldn't make it up any more than the day before you are going to bake it just to be safe.Storage and reheating - This is one of those recipes that is best eaten on the day it's baked. The topping can get a little soggy when you reheat leftovers. But having said that I enjoy it warmed up the next day. Store any leftovers in an airtight container in the fridge for no more than 2 days. You can pop them in a covered dish and bake in the oven on 350°F (175 °C) for 15 to 20 minutes or until piping hot, or microwave for a couple of minutes.