Preheat your oven to 250°F (120°C) and line a large baking sheet with parchment paper or a silicone baking mat.

In a large heat-proof bowl, combine the pretzel crackers and pecan halves.

In a medium saucepan over medium heat, combine the butter, brown sugar, and corn syrup. Stir constantly until the butter has melted.

Bring the mixture to a boil and let it bubble for 2 minutes without stirring. Remove from heat immediately.

Carefully stir in the baking soda and vanilla extract. The mixture will foam up slightly.

Pour the hot caramel mixture over the pretzels and pecans in the bowl. Toss gently with a spatula until everything is evenly coated.

Spread the mix onto the prepared baking sheet in an even layer.

Bake for 45 minutes, stirring the mixture every 15 minutes to ensure it bakes evenly and doesn't burn.

Remove from the oven and immediately sprinkle with flaky sea salt. Let the mix cool completely on the pan; it will crisp up as it cools.

Break apart any large clusters and store in an airtight container.