Prepare the pan: Line a rimmed baking sheet with parchment paper or foil and arrange the pretzels in a single, even layer. Preheat the oven to 350°F.

Make the caramel: In a medium saucepan over medium heat, combine the butter and brown sugar. Stir constantly as the butter melts and the sugar begins to dissolve, creating a smooth, glossy mixture.

Stop stirring when it boils: Once the mixture reaches a full rolling boil, stop stirring completely. Clip a candy thermometer to the side of the pan and let it cook undisturbed until it reaches 290°F (soft crack stage), about 3–4 minutes.

Add flavoring: Remove the pan from heat and carefully stir in the vanilla extract and salt. The mixture will bubble, so use caution.

Pour and bake: Immediately pour the hot caramel evenly over the pretzels, using a spatula to spread it quickly before it sets. Bake for 5 minutes, or until the caramel is bubbly and slightly darkened.

Add chocolate: Remove from the oven and sprinkle the chocolate chips evenly over the hot caramel. Let sit for 2–3 minutes, then spread the melted chocolate into an even layer.

Decorate and cool: Top with holiday sprinkles, then refrigerate or freeze until firm, about 1 hour.

Break and serve: Once set, break into pieces and enjoy!