PREP: Preheat oven to 250 degrees F. Line an extra-large sheet pan (or 2 sheet pans) with parchment paper (or a Silpat liner) and set aside.
EGG WHITES, VANILLA, AND WATER: In a very large bowl, whisk egg whites, vanilla, and water with a fork until frothy. Toss walnuts in egg white mixture until well coated.
SUGARS, CINNAMON, AND SALT: Add white sugar, brown sugar, cinnamon, and salt to egg/walnut mixture. Stir gently to coat all walnuts until well covered. Spread coated walnuts in a single layer onto a baking sheet. Make sure nuts are not overlapping.
BAKE: Bake in preheated oven for 1 hour, flipping and stirring walnuts every 15 minutes. Allow walnuts to stand for 30 minutes up to an hour to fully cool and solidify.
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Notes
STORAGE: Keep at room temperature for 2 weeks. For longer storage, place in a sealed, airtight container in a cool, dark area for up to a month. Alternatively, freeze in an airtight container for up to 2 months. When thawing, remove from the bag and let sit at room temperature to prevent softening or stickiness.Nutritional information is calculated for a one-ounce serving.