1 cup (2 sticks, 1/2 pound) butter*
1 1/2 cups (10 1/2 ounces) sugar
3 tablespoons water
1 tablespoon light corn syrup
2 cups (8 ounces) diced pecans or slivered almonds, toasted
1 pound semisweet or bittersweet chocolate, finely chopped (chocolate chips are an easy solution here; you’ll need about 2 2/3 cups)
*If you use unsalted butter, add 1/2 teaspoon salt.
In a large, deep saucepan, melt the butter. Stir in the sugar, water and corn syrup, and bring the mixture to a boil. Boil gently, over medium heat, until the mixture reaches hard-crack stage (300°F on an instant-read or candy thermometer). The syrup will bubble without seeming th change much for awhile, but be patient; all of a sudden it will darken, and at that point you need to take its temperature and see if it’s ready. (If you don’t have a thermometer, test a dollop in ice water; it should immediately harden to a brittleness sufficient that you’ll be able to snap it in two, without any bending or softness). Pay attention; too long on the heat, and the syrup will burn. And what a waste of good butter and sugar that would be!
While the sugar mixture is gently bubbling, spread half of the nuts, in a fairly closely packed, even single layer, on a lightly greased baking sheet. Top with half the chocolate. When the syrup is ready, pour it quickly and evenly over the nuts and chocolate. Immediately top with the remaining chocolate, then the remaining nuts. Wait several minutes, then gently, using the back of a spatula, press down on the chocolate-nut layer to spread the chocolate around evenly.
While the candy is still slightly warm, use a spatula to loosen it from the baking sheet. When cool, break it into uneven chunks.
Recipe shared from: http://www.kingarthurflour.com/recipes/dark-chocolate-buttercrunch-recipe