Brown beef and onion in skillet, drain off any fat.
Add taco seasoning mix and water. Bring to a boil, then turn down heat and allow to simmer for 5-8 minutes. Turn off heat. Stir in cream of chicken soup until combined well.
Preheat oven to 350F degrees. In a 9 x 13-inch pan, layer ingredients as listed: crushed Doritos, taco meat and 2/3 of the shredded cheese.
Bake uncovered for about 15 minutes (until cheese is fully melted)
Remove from oven and top with finely shredded lettuce, diced tomatoes and remaining shredded cheese.
Drizzle with Catalina dressing. Serve with any of your additional favorite taco toppings.
Video
Notes
I definitely put a dollop of sour cream on top of my serving of the casserole. I also love sliced jalapeños, guacamole and salsa!
If you'd like, you can allow your family to add their own toppings. Put the shredded lettuce, shredded cheese, tomatoes, sour cream, etc. in bowls and everyone can add their favorites!
Instead of Catalina dressing, you can substitute with Russian or French dressing.