Bring larger pot of salted water to boil.
Add green beans, and boil until bright green and about fork tender, about 3 minutes. (remember the beans will continue to cook in oven.
Drain, and cool immediately with cold water to stop cooking process. Set Aside.
In a large skillet, melt the ghee over medium heat and add the mushrooms and onions. Saute until the onions are soft and the mushrooms are wilted, 5-7 minutes.
Stir in the garlic, thyme, and salt and sauté for about a minute.
Stir in the flour, dispersing evenly. Stir in chicken broth, milk, and white wine, whisking into the vegetables.
Bring the mixture to a gentle boil to thicken, and turn off the heat. I like to add a touch of lemon or allowed sour cream for a little tang. Taste and decide for yourself.
Stir in the blanched beans and pour into a pan of your choosing. Size is not overly important as you are just heating the mixture through. 13 X 9 is what I usually use.
Place the pan to the side, covered to keep warm while you make the topping.
Heat a large skillet over medium heat and add your fat for frying.
Place the sliced onions and all the dry ingredients into a bowl and stir.
Add the milk, a little at a time just until there is no dry flour left, like a batter.
When your oil is hot (test a onion and see if it immediately sizzles), add the onions in batches to the skillet. Do not crowd the onions, a single layer important. Flip when golden. Brown up the other side and remove to a paper towel lined plate while you continue with the rest onf the onions. Continue to add oil if the pan becomes dry.
Top the green beans and bake for 30-45 minutes. Casserole should be hot and bubbly.
Recipe via tessadomesticdiva.com