Place broth in a medium saucepan, and bring to a boil. Remove from heat, and stir in the couscous, chickpeas, pesto, 2 tablespoons basil, garlic, salt and pepper. Cover, and let stand 10 minutes, or until the liquid is absorbed. Adjust seasonings. Fluff with 2 forks, and sprinkle with the remaining 2 tablespoons basil.