Preheat oven to 350°F and grease a 9x13-inch baking dish.
In a large skillet over medium-high heat, cook ground beef and chopped onion until beef is browned and onion is softened, about 8-10 minutes. Drain excess fat.
Add taco seasoning, black beans, corn, and diced tomatoes with green chilies to the beef mixture. Stir well and simmer for 5 minutes.
In a separate bowl, mix together sour cream and cream of chicken soup until smooth.
Spread half of the crushed tortilla chips in the bottom of the prepared baking dish. Layer with half of the beef mixture, half of the sour cream mixture, and 1 1/2 cups of shredded cheese.
Repeat layers with remaining tortilla chips, beef mixture, sour cream mixture, and top with remaining 1 1/2 cups of cheese.
Bake uncovered for 25-30 minutes until hot and bubbly and cheese is melted and lightly golden.
Let stand for 5 minutes before serving. Serve with salsa and optional toppings on the side.