Melt butter in a small saucepan over medium heat. While the butter is melting, place enough pretzels on the prepared baking sheet to form a single, even layer.

Once the butter has melted, add the brown sugar and stir well to incorporate. Lower the heat, and simmer the butter-sugar mixture until it caramelizes, stirring occasionally. Be careful not to let it boil.

When the mixture has caramelized, pour it evenly over the pretzels, strafing it back and forth down the length of the sheet. The caramel hardens quickly so it’s important to pour it as evenly and quickly as possible. Bake for 5-7 minutes.

Place the chocolate chips in a microwave safe bowl and microwave on 50% power in intervals of 30 seconds until smooth, stirring the after each interval.

Carefully remove pretzel-caramel pan from the oven, and pour the chocolate over the mixture, strafing it down the length of the baking sheet just as you did for with the caramel layer. Use an offset spatula to smooth out any clumps or thick spots.

Sprinkle sea salt evenly over chocolate before it starts to harden. Allow the baking sheet to harden in the fridge for at least 1 hour.

When the bark has cooled and hardened, remove from the fridge and carefully pull the aluminum foil or parchment paper off the back. Break the bark into pieces and serve.