So, what makes it the best? I am inclined to think that it is the unusual use of salted, roasted nuts. The salt is a wonderful addition, complimenting the flavor of both the caramelized sugar and the nuts. And since most nut brittles use raw nuts, I can only assume that the use of roasted nuts also contributes to the superiority of this brittle. In typical peanut brittle recipes the raw nuts are added in the early stages of the cooking process. They are effectively cooked as the sugar syrup cooks, imparting their flavor to the candy brittle in the process. You would think that this would produce the best flavored brittle...but apparently this is not true. Of course, the presence of cashews, almonds, pecans and hazelnuts in addition to the more usual peanuts doesn't hurt the final product either.
Another important difference in this recipe is the amount of butter used. Most brittle recipes that I have come across use very little butter...and some don't use any. The relatively large quantity of butter in this recipe pushes its flavor and texture in the direction of toffee. Although, I don't think someone tasting this for the first time would think they were eating toffee. They would just think they were eating the best brittle they had ever put in their mouth.
I have only made one small change to this recipe. Since the nuts are added at the end, if they have been kept at a cool room temperature, their addition causes the brittle to become very stiff immediately. I place the nuts in a 300° oven when the sugar syrup starts to boil—this way, when they are added to the syrup, they are the same temperature as the syrup. The brittle stays fluid for a longer period of time and is consequently much easier to spread out into a thin layer.
I would only emphasize a couple of other things for the novice candy maker. Every time you make candy from a recipe that begins with dissolving sugar in water (alone or along with other ingredients), always make sure that all of the sugar is dissolved before you begin to boil the mixture. And always brush down the sides of the pan with a pastry brush dipped in water (or a folded paper towel dipped in water if you don't own a pastry brush) to dissolve any remaining sugar granules. Do this even if the recipe doesn't direct you to. Even one undissolved granule of sugar left in the pan can encourage the entire batch of candy to re-crystallize—either while it is cooking or while it is cooling. As a further protection against crystallization, I never put my candy thermometer into the pan until all of the sugar is dissolved. To protect the thermometer from possible damage caused by a rapid change temperature change, I hold it in a glass of very hot water until I need it.
I have been making and giving this brittle for Christmas gifts every year since I discovered the recipe. I encourage you to make a batch (or two...or three...) and give it away to your family and friends. In the coming years you will experience a surge of pleasure when you give it to someone again and see a pair of eyes light up when they recognize "the" nut brittle.
Salted Mixed Nut Brittle
2 c. sugar
½ c. water
4 oz. (1 stick) unsalted butter
1/3 c. light corn syrup (110 g)
½ t. baking soda
12 oz. roasted salted mixed nuts (peanuts, cashews, pistachios, hazelnuts, pecans and/or almonds)
Fleur de sel (or substitute another coarse sea salt)
In a large saucepan, combine the sugar, water, butter and corn syrup and cook over moderate heat until the sugar dissolves. Wash down the sides of the pan with a pastry brush dipped in water. Increase the heat to medium high and bring to a boil.
Continue to cook, stirring occasionally, until the caramel is light brown and registers 300°F on a candy thermometer—about 10 minutes. Remove from the heat and carefully stir in the baking soda. The mixture will bubble and foam. Stir in the nuts, then immediately scrape the brittle onto a large rimmed baking sheet—either non-stick or well greased (grease the sheet before you begin to cook the brittle so it will be ready when the candy is). Using the back of a large, oiled spoon or heat-proof spatula, spread the brittle into a thin, even layer (the mixture will be stiff, so you’ll have to work at it a bit). Sprinkle with the fleur de sel. Let cool completely, about 30 minutes.
Break into pieces and store air-tight.
Makes slightly less than 2 pounds brittle.
(From Food & Wine, December 2007)
Note: The brittle goes together more easily if you place the nuts in a 300° oven while the syrup boils—that way the nuts don’t bring down the temperature of the candy syrup when they are added.