o Preheat oven to 375 degrees. o Crumble 6 cups of Doritos with your hands into a large mixing bowl. o Add the onion, the chili, the enchilada sauce, tomato sauce and 1½ cups of cheddar cheese to the crumbled Doritos. Stir with a rubber spatula to combine. Place mixture into an 8½ x 11-inch oven-proof casserole dish. o Bake for 20 minutes. o Remove from the oven. Spread the sour cream over the top of the casserole with a large spoon or rubber spatula. Top with remaining 2 cups Doritos. Then sprinkle with the 1/2 cup of the cheddar cheese. o Bake for another five minutes and serve.