Preheat your oven to 375 degrees F. This ensures that your casserole bakes evenly and gets that delicious golden crust on top.
Place a large skillet over medium-low heat and add 2 tablespoons of olive oil. Once hot, add the sliced onion and cook, stirring frequently, until tender and caramelized. This should take about 20 to 30 minutes. You want them golden and sweet.
Next, add minced garlic to the onions, sautéing until fragrant. This will enrich the flavor of your casserole significantly.
Then, add the sliced mushrooms to the skillet. Sauté until they’re tender, absorbing all those lovely flavors.
Season the mixture with salt, pepper, Italian seasoning, and paprika. Stir well to combine and let the mixture cook for a few more minutes.
Once everything is beautifully cooked, divide the mixture in half and set it aside for layering later.
Now, fill a 4-quart pot with about 1/2 inch of water and place a steamer basket inside. Bring the water to a boil and add the green beans. Cover and steam for about 5 minutes until tender. Drain and set aside; they will continue to soften in the oven.
Spray a 9x13 inch casserole dish with cooking spray and spread half of the caramelized onion mixture on the bottom. Layer the green beans evenly on top.
Pour the vegan cream of mushroom soup over the green beans, spreading it evenly.
Top with the remaining caramelized onion mixture, distributing it well.
In a bowl, toss together Panko bread crumbs, slivered almonds, and 1 tablespoon of olive oil. Sprinkle this mixture generously over the casserole.
Cover the dish loosely with foil and bake for 30 minutes until the sauce is bubbling and hot.
Finally, uncover the casserole and broil for a few minutes until the topping is lightly browned and crispy. Keep an eye on it to prevent burning!
While the casserole bakes, prepare the crispy onion rings. Soak the sliced onions in almond milk for 20 minutes. In a medium bowl, combine flour, salt, garlic powder, and ground black pepper. Whisk to combine.
When ready, heat oil in a deep skillet. Working in batches, coat the onion rings in the flour mixture, shaking off excess flour. Fry until golden brown, stirring often.
Once crispy, remove the onion rings and place them on a baking sheet lined with paper towels to drain any excess oil.
After all the onion rings are fried, chop some and leave some whole. Arrange them atop the casserole before serving.
