Combine flour, salt, baking powder, thyme and pepper in a medium-sized mixing bowl; set aside.
Beat egg in a small bowl until frothy. Add milk and 2 tablespoons oil; beat until well blended. Pour into flour mixture; stir until well blended.
Heat remaining 6 tablespoons oil over medium heat in a large skillet. Dip chicken pieces in batter; shake off any excess. Fry chicken for about 10 minutes, turning until lightly browned all over.
Lower heat to very low, cover tightly and simmer for about 30 minutes. Turn pieces periodically to ensure even cooking; add 1-2 tablespoons water during cooking if pan becomes too dry.
Uncover during final 4-5 minutes to allow skin to become crisp. Serve hot or cold.