Step 1

Coat a slow cooker with cooking spray. Lightly coat a 6-quart slow cooker with cooking spray.

Step 2

Whisk the egg whites until foamy. Place the egg whites in the slow cooker and whisk until frothy. Add the brown sugar, butter, vanilla, salt, and cinnamon and stir into a thick syrup.

Step 3

Stir to coat the nuts in the syrup. Add the nuts and stir with a spatula until they are evenly coated.

Step 4

Cover with paper towels and the lid, then cook on LOW for 3 hours or HIGH for 1 hour. Place a double layer of paper towels over the top of the slow cooker to catch condensation. Cover with the lid and cook, stirring every 20 minutes, until nuts are fragrant, lightly browned, and the coating appears dull and not shiny, 3 to 3 1/2 hours on the LOW setting or 1 to 1 1/2 hours on the HIGH setting.

Step 5

Spread onto parchment-lined baking sheets and cool completely. Stir one final time, then pour onto 2 baking sheets lined with parchment paper. Spread into an even layer, separating the nuts as much as possible, and cool completely.

Step 6

Separate nuts and transfer to serving or storage containers. Once cool, break apart any nuts that have stubbornly stuck together and transfer to a serving dish, jar for gifting, or airtight container for storage.