Step 1: Prepare the pretzels
Start by lining a 9×13-inch baking pan with parchment paper or aluminum foil to prevent sticking. Break the pretzels into pieces, or use mini pretzels if you prefer a uniform texture. Spread the pretzel pieces evenly across the bottom of the prepared pan. You want to ensure that the entire base is covered with pretzels.

Step 2: Make the caramel sauce
In a medium saucepan, melt the unsalted butter over medium heat. Once the butter is melted, add the brown sugar and stir constantly until the mixture comes to a gentle boil. Keep stirring for 2-3 minutes, allowing the sugar to dissolve completely. Once the mixture starts bubbling, lower the heat and let it simmer for another 2-3 minutes, stirring frequently. Remove the pan from heat and stir in the vanilla extract for added flavor.

Step 3: Pour the caramel over the pretzels
Carefully pour the caramel sauce over the pretzel pieces in the baking pan. Make sure the caramel is evenly distributed, gently tapping the pan on the counter to help the caramel settle into all the nooks and crannies of the pretzels. Allow the caramel to cool for a few minutes to set slightly before proceeding.

Step 4: Melt the chocolate
In a separate microwave-safe bowl, melt the semisweet chocolate chips in 30-second intervals, stirring after each interval until smooth and completely melted. Alternatively, you can melt the chocolate using a double boiler on the stovetop. If you prefer a thinner consistency for the chocolate, you can add a teaspoon of vegetable oil or shortening to make it more pourable.

Step 5: Top the bars with chocolate
Once the caramel has set slightly, pour the melted chocolate over the caramel and pretzel layer. Spread the chocolate evenly using a spatula to cover the entire surface. If you like, sprinkle chopped nuts such as pecans, almonds, or walnuts on top for an extra crunch and flavor boost.

Step 6: Chill the bars
Refrigerate the bars for at least 2 hours or until the chocolate is completely set and hardened. The longer they chill, the firmer and more cohesive the bars will be. Once the bars are fully set, remove them from the refrigerator and cut them into squares or rectangles.