Mushrooms Stuffed with Spinach, Walnuts, and Melted Mozzarella Cheese

Preheat the oven to 400°F. Lightly oil a large baking pan and set aside. In a large skillet, heat the oil over medium heat. Add the mushroom tops and cook for 2 minutes to soften slightly. Remove from the skillet and set aside.

Chop the mushroom stems finely, and add them to the same skillet. Add the onions and cook over medium heat until softened, about 7 minutes. Add the garlic and cook for an additional minute. Stir in the spinach, walnuts, red pepper flakes, and salt and pepper to taste. Cook for 2 minutes, stirring well to combine.

Fill the reserved mushroom caps with the stuffing mixture and arrange in the baking pan. Top with the vegan mozzarella cheese, and bake until the mushrooms are tender and the filling is hot, about 10-15 minutes. Serve hot.