Heat oven to 350°F. Spray 13x9-inch (3-quart) glass baking dish with cooking spray.
In large bowl, stir together chicken, veggies, soups, tomatoes, chili powder and garlic salt.
Layer one-third of the tortilla pieces in baking dish. Top with one-third of the chicken mixture and 2/3 cup of the cheese. Repeat layers twice, ending with the cheese.
Bake uncovered 32 to 35 minutes or until bubbly.
Most home cooks err by pulling this layered bake too early, relying solely on a timer instead of observing the physical state of the dairy and starches inside the 13x9-inch glass baking dish. When baking at 350 degrees Fahrenheit, visual indicators dictate success long before the clock stops.
Reading Visual Doneness Cues
Relying on a thermometer is impractical for layered casseroles, so monitor the edges of the baking dish for vigorous bubbling that penetrates the entire depth, not merely surface steam. The shredded cheddar jack cheese topping should develop light amber spots across the surface, indicating the milk solids are browning and excess moisture has evaporated. Allow the dish to rest for 15 minutes after removal from the oven to let the gelatinized starches in the corn tortillas set, which prevents the portions from sliding apart when served.
Managing Ingredient Swaps
Substitutions alter moisture levels significantly, meaning swapped ingredients require strategic adjustments to maintain structural integrity. Replacing canned cream of mushroom soup with a homemade roux-based velouté requires adding an extra quarter cup of chicken broth to compensate for lower sodium and water content in scratch-made alternatives. Conversely, using fresh plum tomatoes instead of drained canned Ro-Tel introduces excess liquid that will make the tortillas mushy unless the fresh tomatoes are salted and drained in a colander for 20 minutes prior to mixing.