1. Heat nuts in a 10-inch nonstick skillet over medium-low heat, stirring often, 3 minutes or until toasted and fragrant. Remove from heat, and let cool 5 minutes.
2. Cook pasta according to package directions; drain, reserving 1/4 cup pasta water.
3. Meanwhile, process walnuts and garlic in a blender or food processor 10 seconds or until finely chopped. Add basil, parsley, and 2 tablespoons buttery spread; process 30 seconds or until blended.
4. Melt remaining 1 tablespoon buttery spread in skillet over medium heat; add chicken, and cook, stirring occasionally, 6 to 7 minutes or until lightly browned. Remove chicken from skillet.
5. Add zucchini and bell pepper to skillet, and cook over medium heat, stirring occasionally, 4 minutes or until tender. Return chicken and any accumulated juices to skillet, and cook 1 minute or until chicken is done. Toss hot penne with chicken mixture, pesto, and reserved pasta water. Garnish, if desired.