Spray a 9x13-inch casserole dish with nonstick spray.
Gently crush the chips and set them aside. Two cups should be crushed fine, more like bread crumbs and one cup should be larger chunks, to be spread on top at the end.
In a large skillet, cook the ground beef and onions. Drain any extra grease.
Add the garlic and cook for one minute.
Add the frozen corn, taco seasoning, tomatoes with chiles, and two cups of finely crushed chips.
Remove from heat. Stir in the sour cream two cups of cheese.
Pour into the prepared casserole dish and place in the oven. Bake 5 minutes, until warmed through.
Add one cup of cheese on top, then one cup of loosely crushed Doritos and bake another five minutes until the cheese is melted.
Remove from oven and serve.
This is a great freezer meal. Double your recipe and make a second casserole dish of this delicious meal for later. Hold off on adding the top Doritos and cheese so that you have a fresh crunchy topping when you thaw and bake.
Put the Doritos in a Ziploc gallon bag and smash with your hands or a rolling pin.
For an even quicker cooking time, the ground beef and onions can be cooked ahead of time. Store in the refrigerator for up to 3 days or in the freezer for up to a month.