01 - Line a 9 x 9-inch baking pan with parchment paper, leaving an overhang on two sides for easy lifting.
02 - Combine dark chocolate chips and coconut oil in a microwave-safe bowl. Microwave in 20-second intervals, stirring between each, until completely smooth.
03 - Pour half of the melted dark chocolate into the prepared pan, spreading evenly to the edges. Distribute the crushed pretzels on top and lightly press them into the chocolate. Freeze for 5 minutes.
04 - Remove the pan from the freezer. Drizzle caramel sauce evenly over the pretzel layer and sprinkle with 1/2 teaspoon flaky sea salt. Return pan to freezer for another 5 minutes.
05 - Pour remaining dark chocolate over the caramel layer, smoothing with an offset spatula. Drizzle the melted milk chocolate over the top in a zigzag pattern and sprinkle with chopped pretzel pieces.
06 - Refrigerate or freeze the pan until the chocolate bark is fully set and firm, about 30 minutes.
07 - Using the parchment overhang, lift the solid bark out of the pan and transfer to a cutting board. Cut into 24 bite-sized squares. Store in an airtight container in the refrigerator.