Season chicken with half the salt and half the pepper. In a large skillet melt butter and oil over medium-high heat. Cook chicken until golden brown on all sides, about 15 minutes; adjust heat as needed. Cover pan and continue cooking over low heat for 20 minutes, or until chicken is done; transfer to another dish and hold warm. Meanwhile, in a blender or food processor, finely grind together walnuts, garlic and remaining salt and pepper. Pour off all but 4 tablespoons of pan drippings and heat to medium-high. Add walnut and garlic mixture and sauté for 1 minute, until just golden. Add water and simmer for 5 minutes. Return chicken to pan, turning to coat evenly with sauce. Heat thoroughly before serving. | 
