Preheat the Oven - Set the oven rack to the middle position and the temperature to 400ºF (204ºC).
Flatten the Meat - Place one of the chicken pieces between two plastic sheets or in a plastic bag. Flatten to an even thickness, about ½-inch. Repeat with the remaining pieces. Alternatively, cut in half horizontally for pieces 1-inch thick or larger to make two cutlets.
Toss with Seasonings - In a small bowl, combine kosher salt, cumin, paprika, black pepper, garlic powder, onion powder, and chili powder (if using)—Reserve 1 teaspoon of seasoning mix, then with the remaining, evenly coat both sides of the chicken.
Cook the Chicken - Heat a large skillet over medium heat. Add olive oil. Once hot and shimmering but not smoking, add the chicken. Cook until golden brown, about 5 to 7 minutes. Flip and cook until the internal temperature reaches 160 to 165ºF (71 to 74ºC), about 5 to 7 minutes. Transfer to a clean plate to rest for 5 minutes.
Shred - Use fingers or forks to shred the chicken into smaller pieces. Alternatively, dice into ½-inch pieces. Add the reserved 1 teaspoon of the seasoning mix and combine until evenly coated. Cover and set aside.
Layer the Nachos - Line a 13-by-9 inch rimmed baking sheet or casserole dish with foil. Lightly grease with vegetable oil. Evenly spread about half of the chips on the baking sheet. Top with half of the cheese, followed by half of the chicken. Layer with the remaining chips on top, the rest of the cheese, and chicken. Sprinkle more cheese on top if desired.
Bake - Cook the nachos until the cheese melts, about 6 to 8 minutes.
Load up the Nachos - Top with dollops of sour cream, guacamole, pico de gallo on the cheesy areas to prevent sogginess. Garnish with jalapenos, green onions, and cilantro. Serve immediately while still hot.
Notes
Cheese Substitutions: Medium cheddar, Monterey Jack, or queso asadero.
Use Rotisserie Chicken: Add 3 cups of pre-cooked shredded chicken.
Using a Cast iron Skillet: A sizeable 12-inch skillet is recommended.
Double the Recipe: Double the ingredients and bake on a ½ sheet pan (18-by-13-inch).