Pop 10 cups of popcorn and remove un-popped kernels.
Salt the popcorn liberally.
Melt 1 cup of butter in a medium saucepan over medium-low heat.
Add 1 cup of light brown sugar and stir until mixed.
Bring the mixture to a low boil, cooking for 4 minutes without stirring.
After boiling, add vanilla and stir for 1 more minute.
Remove from heat and add baking soda, stirring to aerate the caramel.
Pour a third of the caramel mixture over the popcorn and fold gently.
Continue adding caramel until popcorn is fully coated.
Pour onto a cookie sheet lined with aluminum foil or a Silpat liner.
Let cool and sprinkle with candy mix-ins before serving.
