Preheat the oven to 350°F.

Start off by opening the canned green beans and draining all but one can of the liquid.

Add the canned green beans into the casserole dish, with one can of beans containing liquid. Also, open a can of cream of mushroom soup, and add it to the green bean mixture.

Stir the green bean mixture, until the green beans are combined with the cream of mushroom soup.

Top the casserole with French fried onions, then place it into the preheated oven. Bake for 20 to 30 minutes or until the green bean casserole is warmed through, and the crispy onions are crunchy.

When the green bean casserole is warmed all the way through, reaching an internal temperature of 165°F, remove it from the oven and let it rest for 5 to 10 minutes before serving. Then serve and enjoy!