01 - Preheat oven to 300°F. Line a large rimmed baking sheet with parchment paper.
02 - Place the mini pretzels in a large mixing bowl and set aside.
03 - In a medium saucepan over medium heat, melt the butter. Add the brown sugar, corn syrup, and sea salt, stirring frequently until the mixture comes to a gentle boil. Simmer for 2–3 minutes until smooth and consistently bubbling.
04 - Remove the saucepan from heat and stir in the vanilla extract until well combined.
05 - Immediately pour the hot toffee mixture over the pretzels. Using a spatula, gently toss until every pretzel is evenly coated.
06 - Spread the coated pretzels in a single even layer on the prepared baking sheet.
07 - Bake for 12–15 minutes, gently stirring halfway through, until the toffee coating is set and bubbly.
08 - Remove from the oven and immediately sprinkle with flaky sea salt to taste. Allow the pretzels to cool completely on the baking sheet.
09 - Once fully cooled, break apart any clumped clusters and transfer to an airtight container for storage.