To make sherry vinaigrette: Pour first 5 vinagrette ingredients in a blender and blend until smooth. using the smaller blender opening, slowly add the oil and blend until smooth. Taste and add more salt and pepper if needed, according to your taste.
Lightly season chicken breasts with olive oil, salt and pepper. Grill chicken breasts until cooked throughout, but still juicy. Set aside to cool, and then slice.
Prepare salad by adding lettuce, chicken breast, gorgonzola, cranberries, grapes, artichokes, pecans and croutons to a large salad bowl. Slowly add just enough vinaigrette to lightly coat the salad and then toss. Serve salad with additional vinaigrette on the side for those who like more dressing.