Using a glass jar with a tight lid, combine the vinegar, mustard, garlic, salt, and pepper, and shake well to blend. Add the oil and parsley and shake.
On 4 plates, arrange the endive leaves like spokes around each plate. Arrange the watercress or spinach in the center. Preheat the broiler, and arrange the sliced apples slightly overlapping in 4 fan shapes, place in broiler pan. Cut the cheese into 4 slices and top each apple fan with slices of cheese. Broil until golden for approximately 5 minutes. Using a spatula, carefully place the apple slices and cheese on top of the endive. Drizzle the dressing over the salads and sprinkle with walnuts.