Blend buttermilk, sour cream, mayonnaise, chipotle peppers, adobo sauce, garlic, lime juice, dill, parsley, chives, onion powder, garlic powder, salt, and pepper until smooth, then chill for 30 minutes.
Cook bacon in a skillet until crispy, remove and reserve 2 to 3 tablespoons of the bacon fat.
Season cubed chicken thighs and cook them in the reserved bacon fat until golden brown and fully cooked to 165°F internal temperature.
Combine cooked chicken, crispy bacon, and chopped green onions in a bowl; mix shredded cheddar and mozzarella cheeses in another bowl.
Spread chipotle ranch sauce on half of each tortilla, add chicken filling and cheese, then fold the tortilla over.
Cook each quesadilla in the skillet over medium heat for 3 to 4 minutes per side until golden brown and cheese has melted.
Let cooked quesadillas rest for 2 to 3 minutes, cut into wedges, and serve with extra chipotle ranch sauce.