Preheat oven to 350°F. Place cashews on a sheet pan and roast, stirring once, for 8-10 minutes, or until just starting to brown lightly.
Meanwhile mix together rosemary, sugar, cayenne, and salt in a large bowl. Stir in melted butter or oil.
Add in hot cashews and toss to combine thoroughly with rosemary mixture
Serve warm or cool to room temperature before serving. Store in air-tight container for up to 1 week.
Recipe adapted from The Barefoot Contessa