Preheat oven to 375°F (190°C) Grease a 9×13-inch baking dish.
Cook the beef In a skillet over medium heat, cook ground beef with onion until browned. Add garlic and cook 30 seconds more. Drain excess fat.
Season Stir in taco seasoning (plus cumin/paprika if using). Mix well.
Mix the filling Add corn, black beans, Rotel tomatoes, cream of chicken soup, and sour cream. Stir until creamy and fully combined. Season with salt & pepper.
Layer the casserole
Spread half of the crushed chips in the baking dish
Add all the meat mixture
Sprinkle 1½ cups cheese
Top with remaining chips and cheese
Bake uncovered for 30–35 minutes, until bubbly and golden.
Rest & serve Let sit for 5 minutes. Garnish with cilantro, jalapeños, or extra sour cream.