Preheat your oven to 200°F (95°C). Line two large, rimmed baking sheets with parchment paper or silicone baking mats. Evenly spread the mini pretzel twists across the prepared baking sheets.

In a medium, heavy-bottomed saucepan over medium heat, combine the butter, brown sugar, and light corn syrup. Stir constantly with a rubber spatula or wooden spoon until the butter is melted and sugar is dissolved, about 3-5 minutes.

Continue heating and stirring until the mixture reaches a robust, rolling boil. Boil for exactly 3 minutes, stirring occasionally, to develop the deep caramel flavor.

Remove from heat and quickly stir in the vanilla extract, sea salt (if using), and baking soda. The mixture will foam up and lighten in color.

Pour the hot toffee mixture evenly over the pretzels. Use a spatula to gently toss and fold until mostly coated.

Place trays in the oven. Bake for 1 hour, stirring every 20 minutes to ensure even coating. The low heat dries and sets the glaze.

Remove from oven. If adding toppings like Heath bits, sprinkle now. Let cool completely on the trays for 60-90 minutes until hardened.

Break into clusters and store in an airtight container. Enjoy as a snack or gift.