DEFROST THE FRICASSEED CHICKEN if frozen. Place the chicken pieces, broccoli florets, broth, and 1/2 cup of the walnuts in an ovenproof casserole or Dutch oven. Cover the casserole, place it in the oven, turn the oven on to 375F and bake for 20 minutes. MEANWHILE, MAKE THE PESTO: Combine the remaining 1/2 cup walnuts, garlic, anchovies, cheese, and olive oil in a blender or food processor and process until blended. Add the basil leaves and puree to a coarse paste. Scrape the pesto into a small bowl and set aside. Place the fricassee sauce in a small saucepan over medium heat, and cook until it is thick enough to coat a wooden spoon, about 10 minutes. Pour the sauce over the chicken and continue to bake, uncovered, another 5 minutes. Remove the casserole from the oven and transfer the chicken and broccoli to a serving dish. Add the pesto to the sauce and mix well. Pour the creamy pesto over the chicken and serve immediately.