Cooking spray, as needed
3 cups granulated sugar
1 cup light corn syrup
3 cups raw hazelnuts
1 tablespoon butter
1 teaspoon salt
2 teaspoons baking soda

Grease a cookie sheet with some of the cooking spray, oil or butter; set aside.

In a medium-sized, heavy-bottomed pot over medium-low heat, heat the sugar, corn syrup and 1/2 cup water, stirring continuously, until sugar has dissolved. As sugar is dissolving, brush down sides pot with a pastry brush dipped in cold water to remove all sugar crystals (any that remain will cause unwanted crystallization).

Increase temperature to medium and continue cooking until candy thermometer reaches 280 F ("soft crack"). Stir in the hazelnuts and continue cooking to 300 to 310 F ("hard crack"). Remove from heat, then add the butter and stir well until dissolved. Add the salt and stir well. Finally, add the baking soda, stirring well (it will bubble and foam!).

Quickly spread brittle out onto prepared cookie sheet and let cool.

Once it has cooled, break into pieces and store in an air-tight container to prevent surface from becoming sticky.

Makes about 2 1/2 pounds.