Step 3: Make the Caramel
In a medium saucepan, melt the butter and brown sugar over medium heat. Stir continuously until the mixture begins to boil. Once boiling, let it cook undisturbed for 3-4 minutes until it thickens and turns caramel-like. Remove from heat and stir in the vanilla extract.

Step 4: Assemble the Layers
Pour the hot caramel evenly over the pretzel layer. Use a spatula to spread it out, ensuring all the pretzels are coated. Place the pan in the oven and bake for 10 minutes, or until the caramel is bubbling.

Step 5: Add the Chocolate
Remove the pan from the oven and immediately sprinkle the chocolate chips over the bubbling caramel layer. Let them sit for 2-3 minutes to allow the chocolate to melt. Then, use a spatula to spread the chocolate evenly over the caramel.