Begin by preheating your oven to 350°F (175°C) to prepare for baking the casserole.
In a large skillet set over medium heat, add the ground beef or turkey. Using a spatula, break the meat apart as it cooks until completely browned and no longer pink. Once cooked, drain any excess fat from the skillet.
To the skillet, add in the drained and rinsed black beans, drained corn, diced tomatoes with green chilies, taco seasoning, and salsa. Stir everything together to combine, and allow it to simmer for about 5 minutes.
Grease a 9x13 inch baking dish with a light coating of cooking spray or olive oil. Begin by layering half of the crushed tortilla chips evenly across the bottom of the prepared dish.
Top the chips with half of the meat mixture, spreading it out evenly. Follow this with half of the shredded cheddar cheese, sprinkling it generously across the meat.
Repeat the layering process: add the remaining crushed tortilla chips on top, followed by the second half of the meat mixture, and finish with the last portion of shredded cheddar cheese.
Cover the entire dish tightly with aluminum foil to retain moisture during baking, then place it in the preheated oven. Bake for 25 minutes.
Once the initial baking time has passed, carefully remove the foil and continue to bake for an additional 10-15 minutes.
After baking, let the casserole cool for about 5 minutes to allow the layers to set before serving.
To serve, spoon out portions of the casserole onto plates and finish with dollops of sour cream on top. Garnish each serving with chopped green onions and fresh cilantro if desired.
Notes
Serve with optional toppings like avocado slices or jalapeños for added flavor.