Line a jelly roll pan with aluminum foil or parchment paper and spread pretzels evenly over the bottom.
Preheat the oven to 350 F.
Melt butter and sugar in a medium saucepan on medium heat. Bring to a boil, stirring continuously until the mixture forms a smooth caramel.
Let the caramel bubble and thicken before pouring it evenly over the pretzels.
Place the jelly roll sheet in the oven for 5 minutes, then remove and sprinkle chocolate chips over the top.
Return to the oven for 1 more minute, then spread the melted chocolate with a spatula and sprinkle generously with sea salt.
Let the pan sit on the countertop for about 5 minutes, then place in the freezer to harden for at least two hours.
Break the bark into pieces and store in an air-tight bag in the freezer.
