Preheat the oven to 350º F. Spray a 9x13 baking dish with nonstick cooking spray.

Bring a large pot of water to a boil. Add the green beans and cook for 2-3 minutes or until they are bright green. Using tongs or a slotted spoon, remove the green beans to a large bowl of ice water. Let cool for 2 minutes and then drain and pour the green beans into the baking dish.

Heat a large, deep skillet over medium heat. Add the slices of bacon in a single layer to the skillet. Cook for 4-5 minutes on each side. Remove the bacon to a paper-towel-lined plate to drain. Chop bacon. Remove all but 1 tablespoon of bacon grease in the pan.

In the same skillet over medium heat, whisk together the cream of celery soup, cream of mushroom soup, milk, Worcestershire sauce, and ground black pepper. Bring to a simmer.
Add ¾ cup sharp cheddar cheese to the sauce mixture. Whisk until smooth.

Pour the sauce over the green beans and toss. Sprinkle the remaining ¾ cup of cheddar cheese, the cooked bacon, and French fried onions over the top of the casserole.

Bake in a preheated oven for 20-25 minutes, or until bubbly.

Sprinkle with minced chives and serve immediately.