1In heavy 2-quart saucepan, heat sugar, butter and water to boiling, stirring constantly; reduce heat to medium. Cook about 13 minutes, stirring constantly, to 300°F on candy thermometer or until small amount of mixture dropped into cup of very cold water separates into hard, brittle threads that break easily. (Watch carefully so mixture does not burn.)
2Immediately pour toffee onto ungreased large cookie sheet. If necessary, quickly spread mixture to 1/4-inch thickness. Sprinkle with chocolate chips; let stand about 1 minute or until chips are completely softened. Spread softened chocolate evenly over toffee. Sprinkle with pecans.
3Let stand at room temperature about 1 hour, or refrigerate if desired, until firm. Break into bite-size pieces. Store tightly covered at room temperature.