Preheat your oven to 250°F (120°C). Line a large baking sheet with parchment paper.
Spread the mini pretzels evenly over the prepared baking sheet, making sure they form a single layer.
In a medium saucepan, melt the butter over medium heat. Stir in the brown sugar and corn syrup until the mixture becomes smooth. Bring it to a gentle boil, stirring constantly, and cook for 3–4 minutes until thickened and bubbling.
Remove the saucepan from the heat and quickly stir in the vanilla extract, baking soda, and salt. The mixture may bubble up as the baking soda is added, so stir carefully.
Pour the hot toffee mixture over the pretzels. Toss gently until the pretzels are evenly coated.
Bake for 45–60 minutes, stirring every 15 minutes to help the toffee coat the pretzels evenly and bake consistently.
Remove the baking sheet from the oven and spread the pretzels out into a single layer. Let them cool completely so the toffee coating hardens.
If desired, melt the chocolate chips and drizzle the chocolate over the cooled pretzels. Sprinkle with chopped pecans or almonds, if using. Allow the chocolate to set before serving.
