• Preheat the oven to 400°
• In a large pot, bring heavily salted water to a boil. Add in green beans and cook for 4-5 minutes or until bright green. Drain and immediately add to a bowl of ice water to stop the cooking process. Cool for one minute and drain again. Set aside
• In a large saucepan, melt butter and add sauteed mushrooms and sprinkle with salt and pepper. Cook 3-4 minutes or until tender
• Add garlic and cook an additional minute. Sprinkle with flour and stir to coat
• Add in chicken stock/broth and bring to a simmer. Cook for 3-4 minutes or until it is thick and pasty.
• Reduce heat to low and add in half and half. Gently simmer for 8-10 minutes or until thick enough to coat a spoon. Taste and season accordingly.
• Remove from heat and add in green beans and ⅓ cup of onions. Stir to combine.
• Pour mixture into a greased baking dish and top with remaining fried onions.
• Bake for 10-12 minutes or until the onions are golden brown and the sauce is bubbling.

Alternatively

• Combine canned cream of mushroom soup with drained green beans and ⅓ cup of fried onions. Pour in baking dish, top with remaining onions, and bake 15-20 minutes