1-First, preheat the oven to 400°F (204°C) and grease a 9×13-inch baking dish with nonstick spray. Heat 1 tablespoon of olive oil in a skillet over medium heat, then sauté ½ cup of diced onion for 2-3 minutes until it turns translucent. Add ½ pound of shredded cooked chicken, 1 ounce of taco seasoning, the drained diced tomatoes, and drained green chiles, simmering the mixture for 5-8 minutes to blend the flavors.

2-Place the 10 hard taco shells standing upright in the greased baking dish and bake them for 5 minutes to crisp up.

3-Remove the dish from the oven and spread about 1 tablespoon of refried beans inside each shell to create a base.

4-Fill each shell almost to the top with the chicken mixture, then sprinkle generously with 2 cups of shredded Mexican blend cheese.

5-Bake for an additional 7-10 minutes until the cheese melts and the shells turn golden brown.

6-Top with optional items like sliced jalapeños, sour cream, salsa, shredded lettuce, or chopped cilantro before serving.