Pop the popcorn kernels using your preferred method. Set aside in a large bowl.
In a saucepan, combine sugar, butter, corn syrup, and salt over medium heat.
Once boiling, stop stirring and allow it to cook for 4-5 minutes until it reaches a light golden color.
Remove from heat and stir in vanilla extract.
Pour the caramel over the popped popcorn and mix gently to coat evenly.
If using nuts, fold them into the popcorn at this stage.
Allow the mixture to cool slightly before forming clusters.
Place formed clusters onto parchment paper to set completely.