The first thing that you need to do is to preheat the oven to 350 degrees F.
Next, put the 1/3 stick butter in a large skillet and melt it by placing it on the stove.
Once the butter is melted, put the ½ cup of diced onions and ½ cup of sliced fresh mushrooms in the melted butter. Fry them over high heat briefly. Wait for the ingredients to turn brownish.
While the onions and mushrooms are being sauteed in butter, pour the three cups of chicken broth in another skillet and put the 2 cups of sliced green beans in it. Boil the mixture on the stove for around 10 minutes.
Once the 10 minutes are up, take out the beans and put them in the onion mixture that you prepared in the third step.
Add one can cream of mushroom soup, 1 can of French-fried onion rings and a pinch or two of House Seasoning to the onion mixture as well.
Use the mixing spoon to stir the mixture. Keep stirring it for a minute or two so that the ingredients are properly mixed.
Now pour the mixture in to the greased 1 ½ quart baking dish and place it in the oven. Allow it to bake for up to 20 minutes.
After the 20 minutes are up, take the baking dish out and top it with 1 cup of grated Cheddar.
Put the dish back in the oven and allow it to bake for another 10 minutes or until it is hot and the Cheddar cheese is melted.
Take the baking dish out. Your green bean casserole is cooked and ready to be served.