Stir together first 4 ingredients in a small saucepan, and cook over medium heat until thoroughly heated.
Place 1 tortilla in a 9-inch pieplate. Spread with 1/2 cup chicken mixture, and sprinkle with 3 tablespoons cheese. Repeat layers of tortilla, chicken mixture, and cheese, ending with tortilla. Cover with foil.
Bake at 425° for 15 to 20 minutes or until thoroughly heated. Uncover and sprinkle with remaining shredded cheese; bake 5 more minutes. Cut into wedges.