Break up about 3-4 oz bleu cheese into the sour cream and mayo. Stir. Adjust the seasoning with salt and black pepper to taste. Thin the dressing out with 1-2 Tbl of heavy cream. Stir and refrigerate for a few hours.
Arrange the chicken halves, end to end on the grate. Broil the chicken for about 15 minutes, basting with the excess marinade every 5 minutes. Re-arrange the the halves after the first 10 minutes. Turn the halves over and broil for another 15-20 minutes, basting and re-arranging as before. Turn the chicken halves for the final time. Season with salt and pepper. Spritze a small amount of malt vineger over them as well. Ladle some of the sour-bleu dressing over the center and wing regions of both of halves, but do not use a large amount or the dressing will drip off. Slide the rack in the oven up one position higher. Broil until the sour-bleu on the chicken skin gets bubbly. Remove the chicken from the oven and allow it to rest for 8 minutes. Serve with the remainder of the sour-bleu, on the side.