This dish will keep you warm and cozy on cold winter evenings.Don't let all of the steps in this recipe intimate you. You can time it so that the potatoes are boiling, the mushrooms are roasting, and the onions are caramelizing all at the same time.
Put the potatoes in a pot and cover with water, bring to a boil and reduce heat to medium-low. Let simmer for about 30 minutes, until the potatoes are fork tender.
Drain the potatoes and return them to the pot. Mash them a little with a potato masher. Stir in the non-dairy milk, vegan butter, nutritional yeast, and chives. Continue mashing until the potatoes reach desired consistency. Season with salt and pepper to taste.
Filling
Preheat oven to 375°. Line baking sheet with parchment paper. Toss the mushrooms and garlic with 1 more teaspoon of oil and spread them out on the baking sheet. Roast for 25 minutes or until tender. Leave the oven on.
While the mushrooms are roasting, sauté the onions in the remaining oil over medium heat with a sprinkle of salt and cook for about 20 minutes, until golden brown and caramelized. Stir them often to prevent them from burning and sticking to the pan.
In a 9″ x 13″ baking dish, mix together the onions, mushrooms, beans, and parsley. Top with the potato mixture. Bake for about 40 minutes, until the potato topping is golden brown.