1. In a medium skillet over medium heat, sauté the diced onion in a small drizzle of oil until softened and translucent, about 3 to 5 minutes. Remove from heat and allow to cool slightly.

2. In a large mixing bowl, combine the shredded chicken, softened cream cheese, diced jalapeño, sautéed onion, 1/2 cup of the shredded cheddar cheese, and ranch seasoning. Stir until everything is evenly blended and creamy.

3. Lightly roll out each sheet of puff pastry into a rectangle about 12 x 16 inches. Cut each sheet into 12 equal squares, for a total of 24 squares.

4. Spoon a heaping tablespoon of the chicken mixture into the center of each puff pastry square.

5. Sprinkle a small pinch of the remaining shredded cheese over each portion of filling.

6. Bring the corners of each square up toward the center and pinch the seams tightly to seal, making sure there are no openings. Place each pastry seam-side down.

7. Arrange the filled pastries in the air fryer basket, leaving space between each one so air can circulate. Cook in batches if needed.

8. Air fry at 400°F for 8 to 10 minutes, or until the pastry is puffed and golden brown and the filling is heated through.

9. Serve warm for the best texture and flavor.