The food processor makes it easy to chop the onions for the crispy topping of this classic green bean casserole. Sauté the chopped onions until golden and crispy, mix them with green beans and a creamy mushroom sauce, and bake it in the oven until the casserole is heated through and the topping is golden and crunchy. This vegetarian casserole is a must-have for holiday dinners and potlucks.
