Grill the chicken or bake it. To bake, heat oven to 400° F. Rinse all the chicken and pat it dry with paper towels, then place it in a baking dish lined with foil. Whisk together the mayonnaise and 2 tablespoons of the pesto in a small bowl. Spread the mixture evenly over the top of each chicken breast. Bake until the chicken is cooked through, about 10 minutes. Meanwhile, peel and cut the potatoes into large chunks. Toss them with the pepper and the remaining pesto and salt. Sprinkle the chicken with the pine nuts and raisins and serve with the potatoes.