Heat oven to 350°F. Spray 13x9-inch (3-quart) glass baking dish with cooking spray. In 12-inch skillet, heat oil over medium-high heat. Add chicken, onion and garlic; cook about 8 minutes, stirring frequently, until chicken is no longer pink in center. Remove skillet from heat.
Stir in tortillas, sour cream, soup, corn, beans, green chiles, taco seasoning mix, salt, cumin and pepper. Pour into baking dish. Sprinkle with cheese and olives.
Cover tightly with foil; bake 30 minutes. Uncover; bake 15 minutes longer or until cheese is melted and mixture is bubbly.
In 6-quart bowl, mix lettuce, tomatoes and green onions. Divide lettuce mixture evenly among individual plates. Top each with baked taco mixture and mango-peach salsa.