A drizzle of melted white chocolate makes a pretty decoration for this dark chocolate dessert.
1. Line 15 x 10 x 1-inch jelly-roll pan with nonstick foil or regular foil coated with nonstick spray. In medium-size saucepan, combine butter, sugar, water and corn syrup. Heat over medium heat to melt butter and combine ingredients. Increase heat to medium high and insert candy thermometer.
2. Cook mixture until golden brown in color and registers 300 degrees F on candy thermometer, about 10 minutes. Do not stir. Remove from heat and remove thermometer. Carefully stir in the chopped pecans.
3. Quickly pour toffee onto prepared pan and spread to edges. Let stand in pan on wire rack for 30 minutes to harden.
4. Melt half of the bittersweet chocolate in microwave on HIGH power for 1 minute. Stir until smooth. Spread over top of cooled toffee bar and refrigerate until firm, about 20 minutes.
5. Once firm, flip entire bar over onto a sheet of waxed paper; remove foil. Melt remaining bittersweet chocolate in microwave on HIGH power for 1 minute. Stir until smooth. Spread over top of toffee bar and sprinkle with pecans.
6. Melt white chocolate in microwave on MEDIUM HIGH power (70%) for 1 minute. Stir until smooth. Transfer to a small heavy duty plastic bag; snip off a small corner. Drizzle over half the bar, and refrigerate 20 minutes.
7. Once chocolate is firm, break bar into bite-size pieces. Store airtight at room temperature, up to 1 month.