Heat a skillet over medium. Add the diced onion and cook 2–3 minutes until softened.

Add the ground beef. Break it up and brown until no pink remains, about 6–8 minutes. Season with salt and pepper.

Drain excess fat from the skillet. Transfer the cooked beef and onion into the crockpot.

Sprinkle the taco seasoning over the beef. Add the drained black beans, corn, and diced tomatoes. Stir gently to combine.

Crush the tortilla chips in your hands or a bag. Layer half of the crushed chips over the meat-and-bean mixture.

Sprinkle half of the shredded cheese over the chips. Repeat the chip and cheese layers, finishing with cheese on top.

Cover and cook on LOW for 4–6 hours. The casserole is ready when heated through and the cheese is melted and bubbly. (If you’re short on time, cook on HIGH for 2–3 hours, checking at the two-hour mark.)

Let the casserole sit 5–10 minutes before serving so it firms up slightly. Serve warm. Enjoy!