- 1/4 cup slivered almonds
- 1/2 pound bacon
- 1 large onion, chopped
- 2 tablespoons olive oil
- 3/4 cup chopped mushrooms
- 1 quart water
- 1 pound fresh green beans, trimmed and cut into 2-inch pieces
- 2 (10.75 ounce) cans condensed cream of mushroom soup (such as Campbell's®)
- 1/2 cup water, or as needed
- 2 cups French-fried onions (such as French's®), divided
- 1 (8 ounce) can sliced water chestnuts, drained
- salt and ground black pepper to taste
- Preheat oven to 275 degrees F (135 degrees C). Spread almonds on a baking sheet.
- Toast almonds in the preheated oven until golden, stirring halfway through, about 13 minutes total. Remove from oven and set aside.
- Increase oven temperature to 350 degrees F (175 degrees C). Grease one 9×13-inch casserole dish.
- Place bacon and onion in a large skillet and cook over medium-high heat, turning occasionally, until evenly browned, 8 to 10 minutes. Remove bacon and onion with a slotted spoon; set aside. Drain excess bacon fat from the skillet; add olive oil. Add mushrooms and cook, stirring, until soft, about 5 minutes.
- Place 1 quart water in a saucepan and bring to a boil. Add green beans and blanch for 2 minutes. Drain in a colander and immediately immerse in ice water for several minutes to stop the cooking process and preserve the bright green color. Drain.
- Pour mushroom soup into a large bowl and whisk until smooth, adding up to 1/2 cup water, until soup is the consistency of thick gravy. Stir in almonds, 3/4 of the bacon-onion mixture (reserving the rest for topping), mushrooms, green beans, 1 cup French-fried onions, and water chestnuts. Mix thoroughly to combine and season with salt and black pepper.
- Pour green bean mixture into casserole dish. Top with remaining bacon-onion mixture and 1 cup French-fried onions.
- Bake in the preheated oven until bubbling and crispy on top, 30 to 45 minutes. Serve hot.