Drain spinach well, pressing between paper towels.
Melt butter in a large skillet over medium heat. Add chopped onion, green onions, and jalapeño; sauté until tender. Remove skillet from heat; stir in spinach, soup, sour cream, and ground cumin.
Layer half each of tortilla chips, chicken, spinach mixture, and cheese in a lightly greased 13- x 9-inch baking dish. Repeat layers, ending with spinach mixture.
Bake at 350° for 10 minutes; sprinkle evenly with remaining cheese, and bake 10 more minutes or until cheese is melted. Garnish, if desired.
Note: For testing purposes only, we used Nacho Cheese Doritos.