Preheat your oven to 350°F (175°C). Spray a 13x9 inch baking dish with nonstick cooking spray.

In a large skillet over medium heat, add the ground beef and cook until browned, about 5 to 7 minutes. Add the chopped onion and sauté until translucent, about 3 to 4 minutes.

Sprinkle the taco seasoning over the beef and onions, stirring to combine. Pour in the water and bring to a gentle boil, about 1 minute.

Stir in the black beans and diced tomatoes with green chiles into the beef mixture. Simmer until the mixture thickens slightly, about 3 to 5 minutes.

In your prepared baking dish, layer Fritos corn chips, half of the shredded cheese, then the beef mixture, and top with the remaining cheese.

Cover with aluminum foil and bake for 15 minutes. Remove foil and bake uncovered for another 5 minutes.

Let the casserole cool for a few minutes, then top with additional Fritos and desired toppings before serving.