Preheat oven to 200 degrees F. Spread puffed corn (and peanuts if using) out on two baking sheets (see body of post for other options.)

In a 2 quart saucepan, melt butter with brown sugar and corn syrup over medium-high heat. Once the butter is melted and mixture comes to a full boil, set timer for two minutes. When time is up, remove from heat and add the baking soda and vanilla. Stir.

Immediately pour over puffed corn, stir to coat and place sheet trays in the oven. Total cooking time will be about 40 to 45 minutes. Stir every 10 minutes. To test for doneness, let one puff corn cool to room temperature. It should be crispy. If not, continue to cook for a few more minutes, stirring as needed.

Remove puffed corn to wax paper or parchment paper covered sheet trays to cool. Break up any large clumps as soon as the puffed corn is cool enough to handle.

Store in an airtight container.