Prepare the Filling

Preheat the oven to 325°F (163°C).

In a large skillet over medium heat, cook the ground beef and chopped onion until browned and fully cooked. Drain any excess fat.

Stir in the Ro-Tel tomatoes, Ranch Style beans, taco seasoning, cream of chicken soup, and water. Let the mixture simmer for 5 to 7 minutes until heated through and well combined.

Assemble the Casserole

Lightly grease a 9×13-inch casserole dish.

Spread a layer of crushed tortilla chips on the bottom of the dish.

Add half of the meat and bean mixture on top of the chips.

Sprinkle with 1 cup of shredded cheddar cheese.

Repeat the layers with more crushed chips, the remaining meat mixture, and finish with the remaining cheese.

Bake and Serve

Cover the casserole with foil and bake for 20 to 30 minutes, or until bubbly and the cheese is melted.

Remove from the oven and let it rest for 5 to 10 minutes before slicing.

Serve warm with sour cream and salsa.