Prepare the pretzel base by mixing crushed pretzels, melted butter, and brown sugar.
Press the pretzel mixture into the base of a lined pan and refrigerate.
In a saucepan, combine sweetened condensed milk, chocolate chips, and vanilla over low heat.
Pour the melted chocolate mixture over the pretzel base and spread evenly.
Prepare the caramel layer by combining sweetened condensed milk, brown sugar, butter, and sea salt in a saucepan.
Let the caramel simmer and thicken before pouring it over the chocolate layer.
Pour the caramel over the chocolate layer and refrigerate.
After chilling, cut into bars and drizzle with melted chocolate and a sprinkle of sea salt.