Pre-heat the oven to 375°F.
Add the olive oil to a large skillet and heat up over medium-high heat. Add the ground beef and cook until no pink remains.
Add the diced onions and cook until soft, about 5 minutes.
Add the taco seasoning, fire roasted tomatoes, tomatoes and chilies and beans and heat through.
Add the sour cream and turn off the heat. Stir until well combined.
Lightly spray a 9 x 13” Casserole dish with cooking spray then take 2 cups of the Doritos and evenly line the bottom of the dish.
Spoon half of the meat mixture over the top of the Doritos then sprinkle with 1 cup of cheese.
Repeat with another layer of the same.
Finish with a light layer of Doritos that are not quite as crushed. Big chunks.
Then just a ½ cup sprinkle of cheese.
Cover with foil and bake in the preheated oven for 30 minutes.
Remove the foil and bake for a further 5-10 minutes, until lightly brown on top.
Sprinkle with a little chopped cilantro then Serve with your favorite toppings (sour cream, cilantro, chopped tomatoes, lime, avocado etc)