In a small bowl, whisk together 1 tablespoon of the blue cheese, the cream and lemon juice. Add salt and pepper to taste.

Rinse the endives and slice into 1-inch thick slices. Discard the tough core.

In a large salad bowl, toss the endive and watercress with the dressing to coat the leaves thoroughly. Sprinkle with the walnuts and remaining cheese. Toss again and serve.