1. Preheat oven to 350°F (175°C) and grease a 9×13-inch casserole dish.

2. In a skillet over medium heat, cook ground beef and diced onion until browned; drain excess fat and stir in taco seasoning.

3. Add enchilada sauce and diced tomatoes with green chilies; simmer then stir in sour cream until blended.

4. Crush half of the Doritos and layer them in the bottom of the prepared dish. Top with half of the meat mixture and a layer of cheese. Repeat layers and finish with remaining cheese.

5. Bake uncovered for 20–25 minutes until cheese is melted and bubbly. For extra crispness, broil for 1–2 minutes, watching carefully.

6. Let rest for 5–10 minutes before serving. Garnish with optional toppings.