01 -
Preheat the oven to 350°F (175°C). Lightly grease a 9x13 inch casserole dish.
02 -
Bring a large pot of water to a boil. Add the trimmed green beans and cook for 5 minutes until tender and bright green. Drain and set aside.
03 -
In the same pot, cook the elbow macaroni according to package instructions until al dente. Drain and set aside.
04 -
Melt butter in a medium saucepan over medium heat. Add flour and stir continuously to form a roux; cook for 1 minute. Gradually whisk in milk, then add garlic powder, onion powder, salt, and black pepper. Stir until thickened, then remove from heat and incorporate shredded cheddar cheese until fully melted.
05 -
In a large bowl, mix together the drained green beans, cooked macaroni, cheese sauce, and condensed cream of mushroom soup. Fold in half of the fried onions. Transfer mixture to the prepared casserole dish.
06 -
Sprinkle the remaining fried onions evenly over the top. Bake for 25 to 30 minutes until the surface is golden brown and casserole is bubbling.
07 -
Let the casserole rest for 5 to 10 minutes before serving to set and enhance flavors.