Preheat oven to 375 F. Line a 9-by-9-inch baking pan with aluminum foil, spray with cooking spray, and set aside. In a large mixing bowl, add 5 to 6 cups chips (about 5 big handful of chips from the bag) and with a wooden spoon or similar, poke and crush the chips to the size of a dime. You don’t want powder, but make them small. Add the chili, beans, salsa, 2 loosely-packed cups cheese (about two-thirds of the package), and stir to combine. Pour mixture into prepared pan and bake for 20 minutes.: The kitchen fills with warm notes when the oven comes on, a small reassuring hum that signals the beginning of a baking ritual. You should feel a slight increase in room warmth, and the air will carry a faint metal scent from the racks. Getting the oven fully to 375 F ensures the casserole bakes evenly, allowing the interior to heat through while the top crisps; if you underheat the oven the dish may end up soggy rather than set. A common mistake is starting with a slightly lower temp and then increasing it midway, which can cause uneven browning, so wait until the oven indicates it has reached temperature before putting the pan in.
After 20 minutes, remove pan from oven and spread sour cream in an even, flat layer over the casserole. Sprinkle 1 to 1 1/2 cups loosely packed cheese (the remaining cheese in the package) evenly over the top of the sour cream. Sprinkle 1 to 1 1/4 cups crushed corn chips over the top and bake for 9 to 12 minutes, or until top is browned to desired level.: The shiny foil makes cleanup effortless and helps lift the casserole from the pan, while the cooking spray prevents sticking. As you press the foil into the corners you will notice a faint crinkle sound, and the pan will look clean and ready. This step is important to preserve the crisp edges and to make serving simpler, because the foil keeps the bottom intact when you lift it out. Avoid skipping the spray, some cheeses can adhere to the foil and tear the final slice when removed.
Serve immediately. Optionally, garnish with a dollop of sour cream, a sprinkling of cheese, or a pinch of chopped cilantro or onion. Store leftovers in a Glad Freezerware container or similar airtight container in the refrigerator for up to 5 days or in the freezer for up to 3 months.: Crushing creates a bed that soaks up sauce and loses the large, unwieldy shards that make slicing difficult. As you press the chips , you will hear a brittle crunch and see small fragments accumulate, like coarse breadcrumbs. Making them dime sized gives pockets that hold sauce while still providing texture; too fine and the base will be pasty, too large and the casserole will fall apart. A very common slip is pulverizing them into dust, which results in a heavy, glue like base instead of a structured layer.
Add the chili, beans, salsa, 2 loosely packed cups cheese, and stir to combine: When the canned chili , beans , and salsa meet the crushed chips , you will notice steam rising slightly if the canned items are warm, and the mixture will take on a cohesive, chunky appearance. Stirring with a spoon distributes the flavors and the initial two cups of shredded cheese fold in to add pockets of melty richness. This mixture should be moist but not soupy; if it seems too wet the casserole will struggle to set. Avoid over stirring which can crush the beans and lead to a paste like texture.
Pour mixture into prepared pan and bake for 20 minutes: As the pan slides into the oven you will hear a faint ceramic or metal shift, and soon the kitchen will be scented with warming tomato and melting cheese . After 20 minutes the edges should look set and the center warm and bubbling slightly. This initial bake gives time for the moisture to distribute and the chips in the base to hydrate just enough. Do not open the oven often during this phase, as temperature loss can prevent proper setting and lengthen cooking time.
After 20 minutes, remove pan from oven and spread sour cream in an even flat layer over the casserole: The heat will be evident as you slide the rack out, and the surface will have small bubbles where the mixture has released steam. Spreading the sour cream creates a cooling creamy veil that moderates spice and allows the top cheese to brown evenly. Work gently to avoid breaking the set base; if you push too hard you can create divots that concentrate moisture and prevent even browning later.
Sprinkle 1 to 1 1/2 cups loosely packed cheese evenly over the top of the sour cream: The second layer of shredded cheese should be scattered so it melts into a golden blanket. You will see distinct shreds pool together and then begin to gloss as they warm. This layer is what gives the casserole its signature gooey finish and browned top, so distribute it evenly for uniform color and texture. Adding too much here can overwhelm the balance and make the top oily as it melts.
Sprinkle 1 to 1 1/4 cups crushed corn chips over the top and bake for 9 to 12 minutes or until top is browned to desired level: The final chips create a crunchy crown that toasts in the oven, providing contrast to the creamy middle. Listen for the faint sizzle as the top warms, and watch the color change from pale to amber to golden brown. Because ovens vary, start checking at nine minutes to avoid burning; a single minute can shift the result from perfectly toasted to overly dark. If you notice uneven browning, rotate the pan carefully to promote an even finish.
Serve immediately: A fresh slice will be warm and slightly gooey with a crisp top, releasing a savory aroma that invites immediate bites. Serving hot maintains the contrast between the crunchy top and soft center, while cooling will firm the casserole. A typical error is letting it sit too long before slicing, which can cool the cheese and make the texture dense rather than tender and flowing.
Optionally garnish with a dollop of sour cream or a sprinkling of cheese: A final spoonful of sour cream or an extra pinch of shredded cheese adds visual appeal and a fresh creamy note. The garnish introduces a cool counterpoint to the heat and can refresh the first bite. Avoid over garnishing, which can mask the carefully balanced flavors baked into the casserole.
Store leftovers in an airtight container in the refrigerator for up to 5 days or in the freezer for up to 3 months: Proper storage preserves texture and flavor, and the cooled casserole should be sealed tightly to prevent drying and odor transfer. When reheating from the fridge, warm gently to restore the creamy texture without burning the edges; from frozen, thaw in the fridge overnight first for best results. A mistake is microwaving from fully frozen, which can heat unevenly and create soggy patches.