Combine corn syrup, brown sugar, vanilla, butter, and peanut butter in the slow cooker.
Cook uncovered on high for about 1 hour, stirring every 15 minutes, until the butter melts and the sugar is dissolved.
Remove any unpopped kernels from the popcorn.
Add the popcorn and peanuts to the mixture in the slow cooker and stir well to coat evenly.
Cover and cook on high for another 1 hour, stirring every 15 minutes.
Uncover and cook on low for 30 minutes, stirring every 15 minutes.
Spread the mixture onto a lightly greased cookie sheet and let it cool completely.
Once cooled, break into pieces and store in an airtight container.
Notes / Tips / Wine Advice:
Serving Tip:Serve as a sweet snack at your next gathering or pack in small bags for easy gifting.Wine Advice:Pair with a sweet wine like Moscato or a light sparkling wine for a fun treat pairing.