Melt butter in a skillet over medium heat. Add onion, and sauté until tender, about 5 minutes. Combine onion, chicken, and next 7 ingredients in a large bowl; toss gently. Spoon mixture into a lightly greased 13" x 9" baking dish. Top with coarsely crushed chips. Bake, uncovered, at 350° for 20 to 25 minutes or until bubbly.