Preheat oven to 400°F to prepare the chicken.
Slice chicken breasts horizontally to create 4 thin cutlets.
Place chicken in a baking dish and drizzle with olive oil, then season with garlic powder, salt, and pepper.
Roast chicken for 20–25 minutes, flipping halfway until fully cooked; let rest and chop into bite-sized pieces.
Increase oven temperature to 425°F for the nachos.
In a medium bowl, combine fire-roasted corn, jalapeño, red onion, cilantro, lime juice, mayonnaise, and Tajín seasoning.
On a large sheet pan, spread tortilla chips and sprinkle half of the pepper jack cheese over them.
Add chopped chicken and then spread the prepared corn mixture evenly on top.
Sprinkle the remaining cheese over all and bake for 10–12 minutes until the cheese melts and bubbles.
Remove from oven and garnish with extra Tajín, cilantro, Cotija cheese, crema or sour cream, and jalapeños.
Serve immediately while hot and enjoy.