1. Beat butter or margarine and brown sugar in a large bowl. Beat in vanilla and egg. Stir in the flour and wheat germ. Press evenly into an 8-inch-square baking pan.
2. Bake in stow oven (325°) 20 minutes, or until lightly browned. Remove from oven.
3. Immediately sprinkle the tops of cookie bars with chocolate pieces. When the chocolate has softened, spread carefully over surface with metal spatula. Cool on wire rack; cut into 16 bars. Store in single layer, covered with foil.