Homemade Crunchy Candy Bar Caramel Corn

16 cups popped popcorn (about 1/2 cup unpopped)
1 cup packed brown sugar
1/4 cup light corn syrup
1/2 cup (1 stick) butter
1/2 teaspoon baking soda
1 teaspoon vanilla extract
15 fun-sized candy bars (examples: Twix, Milky Way, 1000 Grand), chopped
1 cup white chocolate chips
1/2 cup semisweet chocolate chips
1 teaspoon shortening (optional)

1. Pop about 16 cups of popcorn and remove any unpopped kernels. Set the popcorn aside in a large bowl or a brown paper grocery sack.

2. In a medium glass bowl or large glass measuring cup combine the butter, brown sugar and corn syrup. Microwave on high for 1 minute, stir, then repeat heating and stirring a total of four to five times until the mixture is bubbling and hot. Stir thoroughly after each interval so the sugar dissolves and the caramel becomes smooth.

3. Remove the caramel from the microwave and stir in the baking soda, vanilla and a pinch of salt. The baking soda will make the caramel slightly lighter and puffier—this helps it coat the popcorn without being too dense.

4. If you used a bowl, pour the popcorn into a large brown paper grocery sack. If the popcorn is already in a bowl, work directly there. Pour the hot caramel over the popcorn, fold the top of the sack over and stir or shake gently with a wooden spoon to distribute the caramel evenly.

5. Place the folded bag in the microwave and heat for 1 minute, remove and shake well. Return to the microwave for an additional 30 seconds, then shake again to ensure the popcorn is coated uniformly. This short burst of heat helps the caramel set around each piece.

6. Pour the caramel-coated popcorn onto a large jelly roll pan lined with parchment paper and spread it into an even layer.

7. Scatter the chopped candy bars evenly over the warm caramel corn so they stick slightly and become part of the mix.

8. Melt the white chocolate chips in the microwave in 30-second intervals, stirring between each interval until smooth. Stir in 1/2 teaspoon shortening if desired to make the white chocolate glossier and easier to drizzle. Drizzle the white chocolate over the popcorn and candy bits.

9. Melt the semisweet chocolate chips the same way and drizzle over the top to create a contrasting stripe of chocolate.

10. Allow the chocolate to set at room temperature, or chill in the refrigerator for 10 minutes to speed the process. Once the chocolate is firm, break the treat into chunks and transfer to an airtight container for storage.