Pour the popped popcorn into a large brown grocery bag and set aside. Line a baking sheet with parchment paper.
In a large microwave-safe bowl, combine the brown sugar, corn syrup, butter, and salt.
Microwave on high for 1 minute, then stir. Repeat four more times for a total time of 5 minutes, until the caramel mixture is hot, bubbly and thick.
Add the baking soda and vanilla and stir well. Be careful as the mixture will bubble and foam up a bit and it's very hot.
Pour the hot caramel over the popped popcorn and stir gently with a long wooden spoon. No need to worry about completely coating the popcorn at this point.
Fold the bag down a few times, then microwave the caramel corn on high for 1 minute.
Shake the bag well, then microwave again for 1 minute.
Shake again, then microwave for 30 seconds. Repeat one final time, for a total cook time of 3 minutes.
Open the bag and pour the caramel corn out onto the prepared baking sheet.
Melt the white and dark or semisweet chocolate in individual microwave-safe bowls by heating for 20 seconds at a time and stirring well between bursts until melted. It usually takes around 90 seconds to 2 minutes of total heating time.
Transfer the melted chocolate to ziplock bags and snip off a corner to drizzle the chocolate over the caramel corn.
Sprinkle the drizzled popcorn with crushed candy canes, then let sit for 30 minutes until the chocolate has hardened.
Break into chunks and clusters and store in an airtight container for up to 2 weeks.