How do you make a green bean casserole?

Ingredients:

- 1 (10 ounce) package frozen green beans

- 1/2 cup chopped onion

- 1/4 cup chopped celery

- 1/4 cup all-purpose flour

- 1/4 cup butter, divided

- 1 teaspoon salt

- 1/4 teaspoon black pepper

- 1/4 cup milk

- 1/2 cup sour cream

- 1/2 cup shredded cheese (cheddar, Parmesan, or a blend)

- 1/4 cup French's Fried Onions

Instructions:

1.) Preheat oven to 350°F (175°C).

2.) Spray a 9x13 inch baking dish with cooking spray.

3.) In a large skillet, heat 2 tablespoons of butter over medium heat.

4.) Add the onion and celery and cook until softened, about 5 minutes.

5.) Add the flour and stir to combine.

6.) Gradually whisk in the milk and cook until the sauce has thickened, about 2 minutes.

7.) Remove from heat and stir in the salt, pepper, sour cream, and 1/2 cup of the shredded cheese.

8.) In a large bowl, combine the green beans, the remaining 2 tablespoons of butter, and the onion-celery mixture.

9.) Pour the green bean mixture into the prepared baking dish.

10.) Sprinkle the remaining 1/2 cup of shredded cheese and the French's Fried Onions on top.

11.) Bake in the preheated oven for 20-25 minutes, or until heated through and bubbly.

12.) Serve immediately.