Traditionally, a mixture of sugar and water is heated to the hard crack stage corresponding to a temperature of approximately 300 °F (149 °C), although some recipes also call for ingredients such as corn syrup and salt in the first step. Nuts are mixed with the caramelized sugar. At this point spices, leavening agents, and often peanut butter or butter are added. The hot candy is poured out onto a flat surface for cooling, traditionally a granite or marble slab. The hot candy may be troweled to uniform thickness. When the brittle cools, it is broken into pieces.  [1]