Place the chicken breasts in the slow cooker. Add the barbecue sauce, minced chipotle peppers, garlic powder, and salt. Stir to coat the chicken evenly.
Cover and cook on low for 6 hours or on high for 3 hours until the chicken reaches an internal temperature of 165°F and shreds easily.
Shred the chicken directly in the slow cooker using two forks and stir it into the sauce.
Preheat the oven to 400°F. Spread the tortilla chips in a single layer on a large baking sheet.
Spoon the shredded chicken evenly over the chips, then sprinkle the shredded cheddar cheese on top.
Bake for 8 to 10 minutes until the cheese is fully melted and bubbly.
Remove from the oven and top with green onions and cilantro. Serve with sour cream on the side.