Preheat grill to medium heat.
In a small saucepan over medium heat, bring heavy cream
to a boil, stirring frequently. Stir in 3/4 cup blue cheese,
immediately reduce heat, and simmer for 5 minutes, stirring
frequently. Stir in sour cream, vinegar, salt, pepper, and
bacon. Keep warm. Cut each head of lettuce in half through
the core, leaving the core intact. Brush all sides with
olive oil. Grill each half over medium heat for 45 seconds
on each side. Place each lettuce half on a serving plate;
sprinkle with salt and pepper. Garnish with tomato slices;
sprinkle with chopped parsley. Add remaining 1/4 cup blue
cheese to dressing; mix well. Ladle warm dressing over lettuce.
Makes 8 servings.