Prepare a slow cooker by spraying it with cooking spray.
in a large bowl mix the sugar, brown sugar, cinnamon, and salt. Add the mixture to the slow cooker.
In another bowl whisk the egg white and vanilla until its frothy. Add the pecans and coat thoroughly.
Remove the pecans from the egg mixture, and add them to the slow cooker. Stir until the pecans are well coated in the cinnamon sugar mixture.
Cook on LOW for 3-4 hours, stirring every 20 minutes. In the last hour add ¼ cup water and stir well. This will ensure a crunchy coating and help the mixture to harden
Line a baking sheet with parchment paper and spread the pecans onto the sheet to cool. The pecans should be pretty sticky so be sure to separate them!