Preheat oven to 400° F. Cover an 11×17 baking sheet with parchment paper or with heavy duty aluminum foil that’s been lightly sprayed with nonstick spray. Set aside.

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, do not let it boil, stirring occasionally for about 3-5 minutes until it caramelizes.

When the mixture has caramelized, pour it evenly over the pretzels, moving 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.

Sprinkle the chocolate chips evenly over the hot toffee and return it to oven for 1 minute with the heat turned off.

Remove the pan from the oven, and use an offset spatula tosmooth out the chocolate. Sprinkle sea salt evenly over chocolate. Sprinkle broken pretzel pieces over the top and press them into the melted chocolate.

Place the toffee in the baking sheet in the fridge for at least 1 hour to harden and set.

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