Bring a medium pot of water to a boil over high heat. Add the green beans and boil for 5 minutes. Use a slotted spoon to transfer the semi-cooked green beans into a bowl filled with ice water. Allow to cool for 3 minutes, then drain out the ice water, just leaving the green beans in the bowl.

Preheat the oven to 350°F and grease a 9”x9” casserole dish (or 10” cast iron skillet)
with cooking spray or oil. Set aside. If using a cast iron skillet, saute all ingredients in it. If using a 9x9 dish, you can use a large skillet in the upcoming directions.

To your skillet, add the butter and onion and cook over medium heat for 5 minutes. Add the garlic and cook for another 1-2 minutes. Continuing to cook over medium heat, mix in the sliced mushrooms and cook for 5-7 minutes until softened.

Add the flour and mix it into the mushroom-onion mixture until it’s no longer
visible, about 1 minute.

Pour in the broth, milk, Worcestershire sauce, salt and pepper. Bring to a simmer over
medium-high heat and cook for about 5 minutes until it begins to thicken.

Turn off the heat. Add the semi-cooked green beans to the mushroom mixture and stir
together.

Bake for 30 minutes in the center rack of the oven.

Remove the pan from the oven and sprinkle the top of the casserole with the
fried onions. Then, bake for an additional 10 minutes.

Allow to cool for 10 minutes before serving, as the liquid will thicken as it sits.