Make popcorn, salt and set aside.
Heat butter in saucepan over medium heat until melted.
Add the brown sugar and whisk until well incorporated.
Continue stirring until mixture comes to a boil.
Once boiling, allow mixture to simmer over medium heat for 3.5 minutes.
Stir in the vanilla at the 3.5 minute mark and continue to let simmer for 1 minute.
Stir in baking soda.
Once the baking soda begins to activate and the caramel changes consistency, remove from heat. **Should only take a few seconds.
Stir a few more times off the heat before drizzling over popcorn.
Gently mix until coated.
Pour popcorn out onto a Silpat liner.
Sprinkle with sprinkles if using and allow to cool.
Enjoy!
Store leftovers in an airtight container at room temperature.