Preheat a grill to high. Mix the melted butter and hot sauce in a large bowl. Transfer half of the mixture to a small bowl and put near the grill for brushing. Brush the chicken with the olive oil and grill until just marked on the bottom, about 3 minutes. Flip and brush evenly with the hot sauce mixture. Continue grilling, turning as needed and brushing with the sauce, until well-marked and cooked through, about 10 more minutes. Transfer to a cutting board and let rest 5 minutes, then cut into bite-size pieces. Toss with the reserved hot sauce mixture. Puree 3/4 cup blue cheese and the sour cream in a blender until smooth. Add half of the blue cheese dressing to the bowl with the chicken; add the sliced celery and celery leaves, red onion and carrot and toss. Divide the lettuce wedges and chicken salad among plates. Drizzle with the remaining dressing and sprinkle with the remaining 1/4 cup blue cheese.