Preheat the oven to 350 degrees F. Heat a large skillet over medium-high heat. Add the ground beef, onion, and garlic. Cook, stirring frequently, until the beef is browned. Drain off any excess grease. Add the olives, green chiles, tomatoes, taco sauce, and refried beans. Mix well. Cook on low heat for 15 minutes, stirring frequently. Spread a thin layer of the beef mixture in the bottom of a 9x13 baking dish (or other large baking dish). Place a layer of the flour tortillas over the beef mixture. Top with another layer of meat, then a layer of shredded cheddar cheese. Repeat the layers with the remaining tortillas, meat mixture, and cheese, ending with meat and cheese on top. Sprinkle the top of the lasagna with the reserved black olives. Place the dish in the oven and bake at 350 degrees F for 20-30 minutes or until the cheese is melted and the lasagna is bubbly. Remove the burrito lasagna from the oven and let it stand for 5 minutes before slicing and serving.