Spread popped popcorn from each bag on its own silpat or parchment lined rimmed baking sheet. Be sure to leave any unpopped kernels behind. Place the two popcorn filled baking sheets in the oven to keep warm while you prepare the coating.
Melt butter in a medium saucepan. Stir in the sugar, corn syrup and water. Heat to a gentle boil, stirring constantly. Allow to continue boiling for 3 minutes, stirring only a couple of times. Remove from heat and stir in the vanilla and then the baking soda.
Pour half of the mixture over each sheet of popcorn, using a couple of spatulas to toss and coat evenly. Return both pans of popcorn to the oven and bake for 15 minutes. Remove from oven and carefully toss the popcorn again. Spread back out in an even layer and return the pans to the oven for another 15 minutes. Remove pans from oven and toss for a minute or two while it cools, to keep the popcorn from clumping. Allow to cool completely on sheet pan and enjoy!
*Note: Optional peanuts can be added to each pan of popcorn before coating. We use cocktail peanuts, but any salted peanut will do.
Notes
Store in an air-tight container for up to one week.