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