Preheat the oven to 300˚F and line a baking sheet with parchment paper.
In a large bowl, beat the egg white until foamy. Add sugar, cinnamon, salt, ginger, nutmeg and cayenne and stir until well combined. Add the walnuts and fold into the egg mixture until they are evenly coated, then add the melted butter and toss to coat.
Spread the nuts into an even layer on the prepared baking sheet and bake for 20-25 minutes, stirring halfway through. Remove from the oven and let cool until crisp.
Notes
Tip: Cool your candied walnuts on a cooling rack and let them dry completely to avoid a sticky mess.