Preheat your oven to 250 degrees F. Line a baking sheet with parchment paper. Set aside.
Combine the sugar, brown sugar, cinnamon, and salt in a medium-sized bowl and set aside. Place the pecan halves in a large bowl and set them aside.
In a small bowl, beat the egg white and vanilla together until the mixture becomes frothy. Pour the egg white mixture over the pecans and gently stir until they're coated. (see note)
Add the cinnamon sugar mixture to the pecans and stir to ensure they are evenly coated. Spread the pecans in a single layer over the prepared baking sheet.
Bake for 20 minutes. Then remove the baking sheet and stir the pecans. Return the baking sheet to the oven and bake for another 25 minutes or until the pecans are golden and crispy. Do not overbake.
Remove the pecans from the oven and let them cool completely on the baking sheet before serving.
Notes
If the pecans seem to not be coated enough with just the egg white mixture, you can add in 1 tablespoon of water.