Heat oven to 350°F. In 12-inch skillet, cook beef over medium-high heat 5 to 7 minutes, stirring occasionally, until thoroughly cooked; drain. Stir in refried beans, salsa and taco seasoning mix. Reduce heat to medium. Heat to boiling, stirring occasionally.
In ungreased 2-quart casserole, place 2 cups of the broken tortilla chips. Top evenly with beef mixture. Sprinkle with bell pepper, onions, 1 cup of the tomato, the cheese and olives.
Bake uncovered 20 to 30 minutes or until hot and bubbly and cheese is melted. Top baked casserole with lettuce, remaining 1/2 cup tomato and remaining 1/2 cup tortilla chips.