Place the popcorn in a brown paper bag. Fold top over a few times and tape it.
Place in microwave folded side up and microwave 2-3 minutes, or until there are 5 seconds between pops.
Pour popcorn into a large mixing bowl throwing out any unpopped kernels. Set aside.
Spray a medium-sized sauce pan and wooden spoon with cooking oil. Add the butter, sugar, and agave. Heat over medium-high heat stirring constantly until mixture reaches a boil and sugar is completely dissolved.
Remove from heat and add in the vanilla, peanuts, salt, and baking soda.
Spray 2 spoons with cooking oil and slowly pour the caramel sauce over the popcorn, using the spoons to stir and coat the popcorn.
Carefully place popcorn back into paper bag (or a new one is fine). Fold the top over and tape. Microwave another 30 seconds.
Spread caramel corn onto a lined baking sheet to cool.