Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking dish.

In a large skillet, sauté one diced onion until translucent (3-4 minutes). Add ground beef and cook until no longer pink (5-7 minutes). Stir in taco seasoning and ¼ cup of water; simmer for another 3-4 minutes.

Stir in canned chili beans and Rotel tomatoes into the beef mixture, simmer for an additional 3-4 minutes.

In the prepared baking dish, spread half of the crushed tortilla chips, layer the meat mixture, and top with shredded cheese.

Bake uncovered for 15-20 minutes until cheese is bubbly and golden brown.

Let the casserole rest for 5 minutes, then garnish with remaining crushed chips and any optional toppings before serving.