01 - Preheat oven to 350°F. Grease a 9x13-inch baking dish with cooking spray or butter.
02 - Bring a large pot of salted water to boil. Add fresh green beans and cook 4-5 minutes until just tender. Drain immediately and rinse under cold water to stop cooking process.
03 - In a large bowl, whisk together cream of mushroom soup, milk, sour cream, garlic powder, onion powder, black pepper, and salt until thoroughly combined and smooth.
04 - Add blanched green beans, cheddar cheese if using, and French fried onions to the sauce mixture. Stir until all ingredients are evenly coated.
05 - Pour green bean mixture into prepared baking dish. Spread evenly with a spatula, ensuring layer is uniform thickness.
06 - In a small bowl, combine crushed Ritz crackers with melted butter. Mix well until all cracker pieces are lightly coated with butter.
07 - Sprinkle buttered cracker mixture evenly over casserole surface. Bake 30-35 minutes until topping is golden brown and edges are bubbling.
08 - Remove from oven and let casserole rest 5 minutes. This allows sauce to set slightly for easier serving.