Preheat your Oven: Preheat your oven to 400°F (200°C). This is important to ensure your pretzels get that perfect toasty crunch.
Melt the Butter: In a medium saucepan over medium heat, melt 1 cup (226 grams) of unsalted butter.
Add Sugar and Ingredients: Once the butter is completely melted, add in 1 cup (200 grams) of packed brown sugar, 1/4 teaspoon of salt, and 1/2 teaspoon of vanilla extract. Stir continuously until the mixture begins to bubble gently and the sugar fully dissolves, which should take about 3-4 minutes. The toffee mixture should have a smooth, thick consistency.
Prepare the Pretzels: On a large baking sheet lined with parchment paper, spread 4 cups (400 grams) of pretzels in a single layer. Make sure the pretzels are evenly distributed to allow proper coating with the toffee mixture.
Pour the Toffee Mixture: Carefully pour the hot toffee mixture over the pretzels, using a spatula to ensure all pretzels are coated evenly. Bake for 6-8 minutes until the toffee is bubbly.
Add Chocolate Chips: Remove the baking sheet from the oven and immediately sprinkle 1 1/2 cups (255 grams) of semi-sweet chocolate chips on top of the hot toffee pretzels. Allow them to sit for about 2-3 minutes to soften.
Spread the Chocolate: Once the chocolate chips have softened, use a spatula to spread the melted chocolate evenly over the pretzels.
Add Optional Nuts: If desired, sprinkle 1/2 cup (60 grams) of chopped pecans or walnuts over the chocolate layer for added texture and flavor.
Cool and Break Apart: Allow the pretzels to cool completely at room temperature, or you can place them in the refrigerator to speed up the process. Once cool, break the pretzel mixture into clusters.