Sprinkle sugar evenly on a large saucepan over medium-high heat. Allow sugar to melt without stirring, swirling the pan occasionally once it starts to melt to help the sugar melt evenly. Once entirely melted, it will start to color quickly. I like to let it get a good amount of color--a decent golden brown--before adding the walnuts. Once added, stir until they're entirely coated with the sugar and cook for a few more minutes, until toasty brown and fragrant. Pour onto a silpat or foil-lined baking sheet spray with nonstick spray. While warm, separate the nuts from each other and from any pooled caramel. Once cool, coarsely chop.