In small saucepan, melt remaining 1/2 cup chocolate chunks with oil over low heat, stirring until smooth. Drizzle over warm brownies. Sprinkle with remaining 1/2 cup pecans; press in lightly. Cool 20 minutes. Refrigerate 1 hour 30 minutes or until chocolate is set. Cut into squares. If refrigerated longer, let stand at room temperature for 20 minutes before serving.