Place chicken in a lightly greased 9x13 inch baking dish. Season with garlic powder, salt and pepper and garnish with onion slices. Place 1/8 cup of butter or margarine on top of the chicken and bake in the preheated oven for 45 minutes.
Raise oven temperature to 375 degrees F (190 degrees C); Place remaining 1/8 cup butter or margarine on top of the chicken and bake for 30 minutes.
Pour orange-flavored beverage all over chicken, bake for 5 more minutes, and serve.