Preheat oven to 300 degrees.

Mix together the brown sugar, salt, rosemary, and cayenne pepper in a small bowl. In a larger bowl, mix the egg whites together. Mix the walnuts in egg whites until they are all coated. Add the sugar mixture and mix well, until the mixture is evenly dispersed amongst all of the pecans .

Spread on a baking sheet lined with parchment paper and bake about 25 minutes. Remove from oven and cool for a few minutes, then transfer to a plastic or glass container. These will keep in an airtight container for about a week.