Preheat oven to 400°F. Line a sheet pan with parchment paper. Slice the jalapeños in half lengthwise and use a spoon to scoop out the seeds and membrane. Place sliced jalapeños on prepared sheet pan, cut side up. In a large mixing bowl, stir together the cream cheese, half (3 ounces) of the shredded cheddar, and the barbecue sauce. Stir in green onions and chicken and mix until well combined. In a small bowl, drizzle panko with 1 teaspoon olive oil and stir to moisten crumbs. Fill each pepper generously with the cheese and chicken mixture. Sprinkle remaining 3 ounces of shredded Cheddar evenly over stuffed peppers and top with panko crumbs. Bake the stuffed jalapeños at 400°F for 15 minutes or until the crumb topping is golden and the cheese begins to brown. Serve immediately.