1. Heat the coconut oil in a medium saucepan and saute the diced onion, garlic and mushrooms until soft. 
2. Add the chicken broth, coconut milk, nutritional yeast, thyme, mace and salt. Stir to combine.
3. Simmer for 5-6 minutes until it begins to reduce and become fragrant
4. Stir in the arrowroot powder and cook for 1-2 more minutes until thick and creamy. Set aside.
5. If using fresh green beans, you’ll want to steam them before baking the casserole. To do this, place the green beans in a pot with a steamer basket and 1-2 inches of water. Cover with a lid and bring to a boil over medium high heat. Lower the heat and steam for 5 minutes. The green beans should be cooked but still crisp.
6. Transfer the green beans to a casserole dish and pour the cream of mushroom soup over the top.
7. Sprinkle the fried onion rings over the top and bake at 400° F for 20-25 minutes until bubbly around the edges.
8. Serve immediately and enjoy! 

To make the onion rings

1. Prepare the onion by removing the ends and slicing into thin rings. 
2. Heat 2 Tbs of coconut oil in a frying pan on medium high heat.
3. Prepare a plate with paper towels for the onions to cool.
4. Pour the coconut milk and cassava flour into separate bowls. 
5. Begin by coating the onion rings in the cassava flour, dipping in the coconut milk and then repeating with the cassava flour.
6.  Carefully drop the onions into the hot oil and fry for 2-3 minutes per side. Remove from the pan and cool on the paper towel to absorb any excess oil. Repeat with the remaining onions, adding more coconut oil if needed.