Prepare your baking sheet by lining it with parchment paper. Set aside.

In a large skillet over medium heat, melt the butter. Once melted, add the pecan halves and stir to coat them evenly.

Add the granulated sugar, brown sugar, cinnamon, salt, and cayenne pepper (if using) to the skillet with the pecans. Stir constantly as the sugars begin to melt and caramelize. This process should take about 3-5 minutes. Keep stirring to prevent burning.

Once the sugar mixture is bubbling and coats the pecans, stir in the vanilla extract. Continue stirring for another minute until the pecans are well-coated and glossy.

Quickly spread the candied pecans in a single layer onto the prepared parchment-lined baking sheet. Use a spatula to separate any clumps.

Allow the pecans to cool completely on the baking sheet. They will harden as they cool. Once cooled, break apart any large clusters.

Store in an airtight container at room temperature.