• Preheat the oven to 350°F. Spray a 9x13-inch baking dish with non-stick cooking spray. Set aside.
• Bring a large pot of water to a boil. Add green beans and cook until bright green and tender, about 4-5 minutes. While the beans are boiling, set out a large bowl of ice water. When the beans are done, drain and place them in a bowl of ice water to stop cooking. Set aside.
• To a large non-stick skillet over medium heat, add bacon. Cook for 9-11 minutes, or until crispy. Transfer the bacon to a plate. Leave about 2 tablespoons of bacon grease in the skillet, discarding the rest.
• To the skillet with the bacon grease, add the onions and mushrooms. Cook for 3-4 minutes, or until softened.
• Add the garlic and cook for 1 more minute. Remove from heat.
• To a large bowl, add the bacon, cream of mushroom soup, heavy cream, salt, pepper, green beans, and the onions and mushrooms mixture. Stir to combine.
• Transfer to the prepared baking dish. Bake for 30 minutes.
• While the casserole is baking, prepare the fried onions.

Fried Onions

• Line a large baking sheet with two layers of paper towels. Set aside.
• To a medium saucepan over high heat, add onions and oil. Cook, stirring constantly, until onions turn pale golden brown, 18-20 minutes. Using a fine mesh strainer, carefully remove the fried onions from the hot oil. Place them in an even layer onto the prepared baking sheet. Sprinkle with salt. Set aside.
• After 30 minutes, remove the dish from the oven. Sprinkle the fried onions evenly on top of the casserole.
• Return the dish to the oven and bake for an additional 10 minutes, or until the casserole is bubbly and the onions are golden brown. Serve warm.