Preheat your oven to 350°F (175°C).
In a large skillet over medium heat, cook the ground beef until browned, about 5-7 minutes. Drain any excess fat.
Stir in the taco seasoning mix, black beans, corn, and salsa. Cook for an additional 5 minutes until heated through.
In a 9x13 inch baking dish, layer half of the crushed tortilla chips on the bottom.
Pour the beef mixture evenly over the chips, then sprinkle half of the shredded cheddar cheese on top.
Add the remaining crushed tortilla chips and top with the rest of the cheddar cheese.
Bake in the preheated oven for 20-25 minutes, or until the cheese is melted and bubbly.
Remove from the oven and let it cool for 5 minutes. Top with sour cream, sliced green onions, and diced avocado if desired.
