1 cup (2 sticks) of unsalted butter
1 cup light brown sugar
6-oz each of semi-sweet chocolate chips and bittersweet chocolate chips
Line a small rimmed baking sheet with tin foil and cover the baking sheet in a single even layer of mini pretzels.
Preheat the oven to 400 degrees.
Melt the butter in a saucepan over medium heat. Once the butter is melted, add the sugar and stir to incorporate. Allow the sugar and butter to simmer (but don’t let it boil), stirring occasionally until the caramel is lovely and golden brown, about 3 minutes. Pour the caramel evenly over the pretzels on the baking sheet. Strafing it back and forth down the length of the sheet works well. The caramel hardens pretty quickly so it’s important to pour it as evenly as possible. If you end up with any clumps, just use a spatula to spread the caramel as best you can. Bake the pretzel-caramel mixture in the oven for 5-7 minutes.
In the meantime, set up a double boiler. Fill a saucepan about a quarter ways full with water. Place the pot over a medium flame. Take a large, heatproof bowl and set it on top of the saucepan. Pour the chocolate chips into the bowl and stir constantly until they’re completely melted.
Pour the chocolate over the pretzel-caramel mixture evenly, again strafing the melted chocolate back and forth down the length of the sheet. Spread any remaining thick spots of chocolate with a spatula. Sprinkle sea salt evenly over the bark.
Place it in the freezer to cool and harden for an hour or two. Serve cold.