Preheat the oven to 200 degrees F (95 degrees C). Prepare a jelly roll pan with cooking spray.

Beat egg white and sugar together in a large bowl.

Mix cinnamon, vanilla, and salt together in a small bowl; stir into the egg mixture. Fold walnuts into the mixture to coat; spread onto the prepared jelly roll pan.

Bake in the preheated oven until the coating is crusty, about 1 hour 15 minutes. Cool nuts 5 minutes before serving.