In a large skillet over medium heat, cook the ground beef and onion until the meat is brown and no longer pink. Add the garlic. Stir. Cook for 1 minute more.
Turn the heat to low. Add the salsa, black beans, refried beans, enchilada sauce, diced green chilies, and taco seasoning. Heat until warm.
Preheat the oven to 375°F. Grease a 9" x 13" inch pan. Place 1 1/2 cups of the meat mixture in the pan. Spread to cover the bottom of the pan. Layer 2 tortillas over the meat mixture. Add a third of the remaining meat mixture over the tortillas and 1 cup of cheese. Repeat layers. Top with the remaining tortillas and meat mixture.
Cover and bake for 30 minutes. Uncover. Top with remaining cheese and crushed tortilla chips. Bake for 10 minutes or until the cheese is melted.
Garnish with olives, sour cream, guacamole, tomatoes, and cilantro if desired.