0 Preheat the oven to 350 F.
1 In a 13-inch cast iron pan, or 9x13 inch oven-safe pan, heat the oil over medium heat, add the diced onions and garlic and saute 5 to 7 minutes, until onion is translucent. Add the ground beef, salt, and pepper, and cook 7-8 minutes until ground beef is browned and fully cooked. Remove from pan.
2 Add the 3 tablespoons oil to the pan, then add hash browns. Cook 5 to 6 minutes, then flip, and cook an additional 3-4 minutes, or until the potatoes are crispy and cooked through. Place the ground beef and onion mixture on top of the hash browns, then pour on the nacho cheese.
3 Put the pan in the oven and bake for 15 minutes. While casserole is baking, prepare the toppings.
4 Once casserole has finished baking, garnish with the lettuce, bacon, tomato, avocado, and jalapeno and serve!
