Preheat the oven to 400°F (200°C). Line a baking sheet with foil and lightly spray with nonstick spray; set aside.
Heat 1 tablespoon olive oil in a large skillet over medium heat. Add the chopped chicken and cook until no longer pink and the internal temperature reaches 165°F (74°C), about 6–8 minutes depending on pieces. Remove chicken and keep warm.
Discard any excess liquid from the skillet, then heat the remaining 1 tablespoon olive oil over high heat. Add the diced purple onion and corn and cook, stirring occasionally, until they begin to lightly char, about 3–4 minutes.
Return the cooked chicken to the skillet and stir in the black beans, lime juice, ground cumin, chili powder, and chopped cilantro. Mix until combined and remove from heat.
Arrange the tortilla chips in an even layer on the prepared baking sheet. Spoon the chicken and vegetable mixture evenly over the chips, then sprinkle the shredded cheddar cheese on top.
Bake in the preheated oven for about 10 minutes, or until the cheese is melted and bubbly.
Remove from the oven and immediately top with shredded romaine lettuce, diced tomatoes, jalapeño slices, and avocado slices. Serve hot.