Spoon one-third of sauce onto bottom of a lightly greased 13- x 9-inch baking dish; top with 3 tortillas. Spoon half of beef mixture and one-third of sauce over tortillas; sprinkle with half of Cheddar cheese. Top with 3 tortillas; repeat layers ending with tortillas. Sprinkle with Monterey Jack cheese and next 3 ingredients. Bake for 30 minutes. Top with avocado.