Preheat oven to 350°F. Line a 13x9x2-inch baking pan with foil; lightly coat foil with nonstick cooking spray. Set aside. In a medium bowl, lightly beat the egg white with a fork until frothy. Add rosemary, pepper and salt, beating with the fork until combined. Add nuts; toss to coat.
Spread nut mixture in an even layer in the prepared pan. Bake for 15 to 20 minutes or until golden, stirring once.
Remove foil with nuts from pan; set aside to cool. Break up any large pieces. Store in an airtight container in freezer for up to 1 month.