Toffee Butter Crunch

1 cup butter (2 sticks)
1 cup sugar
1 tablespoon light corn syrup
¾ cup semisweet chocolate pieces
½ cup plus ½ cup chopped toasted pecans

Melt butter in a large saucepan. Add sugar and corn syrup. Cook over medium heat, stirring often, to hard-crack stage (300º) watch carefully after temperature reaches 280º. Quickly stir in pecans; spread in well-greased 13x9" pan. Cool thoroughly. Turn out on waxed paper; spread top with half the melted chocolate; sprinkle with ¼ cup pecans. Cover with waxed paper; invert; spread again with remaining chocolate. Sprinkle top with remaining nuts. If necessary, chill to firm chocolate. Break into pieces.