Season chicken with salt and pepper then saute in a large, nonstick-sprayed skillet over medium-high heat until cooked through.
Remove to a plate to cool slightly.
In a very large bowl add enchilada sauce, sour cream and salsa then whisk to combine.
Add cooked chicken, corn, and green chilies then stir to combine.
Add corn tortillas then stir to combine.
Spray a 9x13" casserole dish (or 2 smaller baking dishes) with nonstick spray then scoop mixture inside.
Top with cheese then bake for 25 minutes, or until golden brown and bubbly.
Let rest for 5 minutes before serving.
Top with green onions and salsa, if desired.
Replacing the white corn tortillas with chickpea-based tortillas alters both the structural integrity and protein density of the dish, though standard corn tortillas absorb the sauce best without turning gummy. Professional kitchens rely on specific thermal controls when preparing baked casseroles in advance.
Freezing and Make-Ahead Mechanics
Assembling this casserole up to 24 hours before baking requires wrapping the unbaked 9x13-inch dish tightly in two layers of plastic wrap followed by a layer of aluminum foil to prevent freezer burn. Raw dairy products like low-fat sour cream can separate when frozen, so for optimal texture when freezing long-term, omit the sour cream from the sauce base and stir it into the warm chicken mixture just before transferring everything to the baking dish. Store unbaked casseroles in the freezer for up to two months. Defrost frozen casseroles completely in the refrigerator for 24 hours prior to cooking, as baking straight from a frozen state results in uneven heat penetration where the edges burn before the center reaches 165 degrees Fahrenheit. Bake defrosted casseroles covered in foil at 350 degrees Fahrenheit for 20 minutes, then remove the foil and bake for an additional 10 minutes until the cheddar cheese bubbles and browns.
Reheating and Second-Day Transformations
Leftovers stored in an airtight container remain safe for consumption for up to four days at 40 degrees Fahrenheit or below. Reheating individual portions in a microwave works, but crisping the edges yields superior flavor; place portions in a cast-iron skillet over medium-low heat with a tablespoon of water covered by a lid for 5 minutes. Transforming day-old portions involves chopping the chilled casserole into patties, dredging them in beaten egg and crushed tortilla chips, and pan-frying them in neutral oil at 375 degrees Fahrenheit for 3 minutes per side until a crust forms.