Prep and blanch the green beans by trimming the ends and cutting them into 1–2 inch pieces. Boil them for 3–5 minutes until bright green and tender-crisp, then transfer to an ice bath.

Make the creamy mushroom sauce by melting the butter in a saucepan, sautéing mushrooms, stirring in flour, then whisking in vegetable broth and cream.

Combine the blanched green beans with the creamy mushroom sauce in a mixing bowl, then pour into a greased baking dish.

Prepare the fried shallots by heating oil in a skillet and frying the shallots until golden brown and crispy.

Bake the casserole in a preheated oven at 375°F for 20 minutes covered with foil, then add the fried shallots and bake for another 7–10 minutes.