To make the dressing, place buttermilk, yogurt, apple cider vinegar, Worcestershire sauce, chives, garlic, cayenne, sea salt and fresh ground black pepper in a blender. Process until smooth. Refrigerate until ready to serve.
Meanwhile, heat a grill pan or skillet to medium-high heat. Spray with oil.
Season chicken breast with salt and pepper and cook until golden brown on both sides, about 8 minutes per side. The internal temperature should be 165° F.
Transfer to a cutting board and allow to cool for 10 minutes before slicing.
Place romaine in a large bowl and toss with bacon, chicken, avocado, tomatoes and blue cheese. Add desired amount of dressing and toss until evenly coated. Serve immediately.