Green Beans:
Trim the ends of the beans and then cut into 2-inch long pieces.
Bring a large pot of water to a boil. Carefully add the green beans to the water using a slotted spoon and boil for about 4-5 minutes, or until crisp tender. Begin checking on them after 3 minutes to ensure they do not overcook. Drain the green beans in a colander in the sink.
Fried Onions:
Preheat the oven to 425 degrees.
Cut the onion into thin slices that are 2-inches long.
Add flour to one medium-sized shallow bow. Whisk together the egg and milk in a second shallow bowl. Mix the breadcrumbs, salt, pepper, and garlic powder in a third shallow bowl.
Dip a few of the onion strips in the flour, dredge in the egg wash, and then coat with the breadcrumbs. Lay them on a parchment paper lined baking sheet and repeat this until all of the onion pieces are completely covered.
Bake in the preheated oven for 15-20 minutes, flipping halfway through. They should be lightly golden and crispy when done.
Cream of Mushroom:
While the onions are cooking, add the butter to a large skillet over medium heat along with the mushrooms. Saute for 4-5 minutes, or until softened. Add the minced garlic and continue sauteing for 30 seconds, or until fragrant.
Sprinkle in flour and stir until thickened. Immediately begin pouring in the broth in ¼-cup increments, whisking well after each addition. Wait until the sauce has thickened up to add in the next amount. Once all of the broth has been added, pour in the milk in ¼-cup increments as well, whisking and waiting for it to thicken after each time.
Season the cream of mushroom soup with the salt, pepper, and dried thyme.
Add the boiled and drained green beans to the skillet and toss until they are well coated.
Spray a 13x9-inch baking dish with non-stick cooking spray and pour in the green beans. Sprinkle the fried onions on top.
Reduce the oven temperature to 400 degrees and bake for 15-20 minutes. Let sit at room temperature for 10 minutes before serving. Enjoy!