Pop the popcorn according to the directions on the bag. Set aside.
Add the brown sugar, butter, and corn syrup to a microwave safe bowl and microwave for 2 minutes, stirring halfway through.
Stir until mixture is combined, about 30 seconds.
Add the pumpkin pie spice, vanilla extract, and baking soda to the bowl and stir vigorously until well combined and smooth.
Add the popcorn to a large mixing bowl and pour the caramel over the top. Stir to coat.
Microwave in the bowl for 30 seconds to firm up the caramel.
Spread coated popcorn onto a parchment lined baking sheet.
Melt the white chocolate chips in the microwave in 20 second bursts, stirring each time, until melted.
Drizzle over the popcorn and let sit until hardened, about 30 minutes.