Preheat oven to 225° F. Line a large rimmed baking sheet with parchment paper and set aside.
In a large bowl, whisk egg white vigorously until frothy, about 30 seconds. Whisk in remaining ingredients (vanilla, brown sugar and spices). Stir in pecan halves until coated.
Transfer pecans and any liquid to prepared baking sheet. Spread into an even layer.
Bake at 225° F for 1 hour, tossing the pecans every 15 minutes and spreading into an even layer. Remember to close the oven door when tossing the nuts so the heat doesn't escape. Let the pecans cool completely, which will allow them to become crispy. Enjoy as is, use as garnish on a dessert or give as a gift for the holidays.
Notes
For more spicy pecans, use aleppo pepper. If you can't find it, use chili powder and increase cayenne pepper to 1/4 teaspoon.For less spicy pecans, use chili powder instead of aleppo powder and omit the cayenne.Store in an airtight container for up to 2 weeks.Freeze nuts in a freezer bag with the air removed for up to 1 month.