In a shallow baking pan spread nuts in a single layer. Bake in a 350 degrees F oven for 8 to 10 minutes or until nuts are toasted, stirring once.
In a medium saucepan melt butter over medium heat. Add brown sugar; cook and stir until sugar melts. Remove from heat. Stir in thyme, salt, and, if desired, cayenne pepper. Add nuts to butter mixture; toss to coat. Spread nut mixture on a piece of foil. Cool.
To store, place cooled nuts in an airtight container; store in refrigerator for up to 1 week. Freeze for longer storage.
Makes about 2 cups.