Boil a large pot of water for the green beans and set the oven to 375.
Trim green beans if untrimmed, then cut them in quarters.
Boil the green beans for about five minutes, then put them in an ice bath and drain.
Once the beans are dry, add them to a large bowl.
Add the cream of mushroom soup, cup of shredded cheddar and one egg to the bowl as well. Mix to combine and add to a baking dish.
Now, slice an onion in half and then cut into strips.
Heat the olive oil over medium heat.
Beat the other egg in a bowl.
Add the cassava flour to another bowl.
Dip the onions in the egg, then dredge them in the flour. Make sure the flour is really covering them.
Add them to the hot olive oil. Once they start to brown, flip them.
Add the onions to the top of the casserole and bake for about 30 minutes of 375.