Combine Ingredients: Stir in the beans, Ro-tel tomatoes, chopped onion, taco seasoning, cream of chicken soup, and water to the skillet. Simmer over medium-low heat until everything is well combined and heated through.
Assemble Casserole: Grease a 9×13 inch casserole dish.
Layer with crushed tortilla chips.
Top with the meat and bean mixture.
Sprinkle with half of the shredded cheddar cheese.
Repeat layers.
Bake: Cover the casserole dish with foil. Bake at 325°F for 20-30 minutes, or until bubbly and heated through.
Serve: Let the casserole sit for 5-10 minutes before serving. Top with sour cream and salsa.
Tips & Variations:

Add some spice: Include a diced jalapeño or a sprinkle of red pepper flakes to the meat mixture for extra heat.
Make it vegetarian: Substitute the ground beef with plant-based ground meat or lentils.
Get creative with toppings: Experiment with different toppings, such as avocado slices, chopped cilantro, or diced green onions.
Enjoy this hearty and delicious Mexican Casserole!