Heat sugar, butter and water to boiling in heavy 2-quart saucepan, 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. Watch carefully so mixture does not burn.
Immediately pour toffee onto a large cookie sheet lined with parchment paper. 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.
Let stand at room temperature about 1 hour, or refrigerate if desired, until firm. Break into bite-size pieces. Store in airtight container. Enjoy!