1

Line a baking sheet with foil measuring approximately 13x17".

2

Combine sugar, butter, water and vanilla in a heavy saucepan. Cook over low heat, stirring constantly until light brown and hard crack stage (290-300 degrees on a candy thermometer). This should take about 20 minutes.  Pour toffee onto foil, spreading smoothly and quickly into 6x12" rectangle. Cool. Carefully transfer candy to waxed paper. It breaks quite easily.

3

Melt half of the candy bar and spread on top of the toffee. Sprinkle with ½ cup pecans, pressing into chocolate firmly. Refrigerate until set. Melt the other half of the candy bar. Turn cooled toffee over and spread remaining chocolate over the surface. Sprinkle with remaining pecans, pressing into chocolate firmly. Cool and break into pieces.

4

Store cooled toffee in an airtight container.