Line an 8×8 inch square baking pan with parchment paper, leaving a bit of overhang on the sides to make it easy to lift the bars out later. Crush your pretzels into coarse crumbs using a food processor or a rolling pin and a sealed bag, then set them aside in a large mixing bowl.
In a small bowl, combine the melted butter and brown sugar until the sugar is mostly dissolved. Pour this mixture over the crushed pretzels and stir until every crumb is well coated. Press the pretzel mixture firmly into the bottom of your prepared pan to create an even layer, then place the pan in the freezer for 10 minutes to set.
In a medium microwave-safe bowl, combine the caramel bits and the heavy cream. Heat in 30-second intervals, stirring well in between, until the mixture is completely smooth and melted. Be careful not to overheat the caramel, as it can become too hard once it cools back down.
Once the caramel is smooth, stir in the alcohol-free vanilla extract for a boost of flavor. Pour the warm caramel over the chilled pretzel base and spread it quickly with a spatula to reach all the corners. Return the pan to the refrigerator for about 15 minutes to allow the caramel to firm up slightly.
In another microwave-safe bowl, combine the chocolate chips and coconut oil. Melt the chocolate in 30-second bursts, stirring until the mixture is glossy and smooth. The coconut oil helps the chocolate stay a little softer so it does not crack when you bite into the bars.
Pour the melted chocolate over the caramel layer and smooth it out with a spoon. While the chocolate is still wet, sprinkle the coarse sea salt over the top to your liking. Refrigerate the bars for at least two hours, or until completely firm, before lifting them out by the parchment paper and slicing them into squares.
