Preheat the oven to 375°F (190°C).
In a mixing bowl, combine the shredded cooked chicken, olive oil, taco seasoning, diced onion, drained diced tomatoes, and drained diced green chiles. Mix thoroughly.
Place hard taco shells upright in a baking dish. Spoon a layer of refried beans, followed by the chicken mixture, and top with shredded cheese.
Bake in the preheated oven for 15-20 minutes until cheese is melted and bubbly, and taco shells are crisp.
Remove from the oven, let cool briefly, and top with jalapeños, sour cream, salsa, lettuce, and cilantro.
