1. Preheat broiler to high.
2. Cut each chicken breast half in half lengthwise to form 2 cutlets. Sprinkle with 1/4 teaspoon salt and 1/4 teaspoon pepper. Heat a grill pan over medium-high heat. Coat pan with cooking spray. Add chicken to pan; cook 4 minutes on each side or until done.
3. Combine artichokes, 3 tablespoons cheese, nuts, mayonnaise, oil, 1/4 teaspoon salt, 1/4 teaspoon pepper, and garlic in a mini food processor; pulse until coarsely ground.
4. Place bread slices on a baking sheet; broil 1 minute on each side. Spread 2 1/2 tablespoons pesto on each slice. Slice chicken; place 3 ounces on each bread slice. Top evenly with remaining 5 tablespoons cheese and parsley.