In a large skillet over medium heat, add 2 tablespoons of oil and let it warm for a moment. Toss in the sliced mushrooms and cook for about 4 minutes until they begin to brown. Then, add the minced garlic, diced red onion, and bell peppers. Sauté everything together for another 3-4 minutes, stirring until the veggies soften, and finally incorporate the baby spinach until it wilts.

Preheat your oven to 375°F. Generously spray a 9x13 inch baking dish with cooking spray to prevent sticking. Once the sautéed vegetables are ready, set them aside. Now, layer the thawed and shredded potatoes evenly across the bottom of the baking dish, pressing down gently to create a solid base.

In a large mixing bowl, crack 10 eggs and whisk them together until well beaten. Stir in ⅓ cup of half and half or milk, along with ¼ cup of hot sauce, salt, and pepper to taste. Mix these ingredients thoroughly until combined.

Spread the sautéed vegetable mixture evenly over the layered hash browns. Carefully pour the egg mixture on top of the veggies and potatoes, ensuring even coverage. Sprinkle 1 cup of your choice of shredded cheese across the top.

Place the baking dish in the preheated oven and bake uncovered for 45–50 minutes. Keep an eye on it; it will be ready when the top is golden and the eggs are fully set.

Once baked to perfection, remove the casserole from the oven and let it cool for about 10 minutes before slicing.