Heat oven to 300°. Line a baking sheet with parchment paper; set aside. Mix dark brown sugar, paprika, cayenne, salt, coriander, garlic, cumin, and allspice in a bowl. Mix pecan halves and egg white in a bowl until combined. Toss nuts with spice mixture to coat completely. Spread on prepared baking sheet; bake until browned and crisp, 25–30 minutes. Let cool before serving.