Make the Shortbread: Preheat the oven to 325 degrees F. Line a 13×9 inch baking pan with parchment paper and set aside. In the bowl of a stand mixer, add softened butter and mix until smooth. Add the confectioners sugar and mix well until fully incorporated. Add vanilla and mix 30 seconds more. Scrape down sides of the bowl as needed. With mixer off, add in flour and salt and mix on low until fully blended. Spread cookie dough evenly into prepared baking pan. Bake in preheated oven for approximately 18-22 minutes or until cookie dough is golden brown in color. Remove from oven and set aside to cool.
Prepare the Caramel: In a medium saucepan, heat the sugar over medium heat, stirring constantly with a wooden spoon or heat resistant rubber spatula. Sugar will first form clumps then melt into an amber colored liquid. Continue to stir until all sugar is melted, being careful not to burn the sugar. Add the butter, being careful as the sugar will bubble up when the butter is added. Continue stirring until the butter is completely melted. Use a whisk to fully incorporate the butter into the melted sugar. While continuing to whisk, slowly drizzle in the heavy cream, being careful as the mixture will bubble up and may splatter when the cream is added. Allow the caramel to boil for 1 minute; it will rise in the saucepan as it boils. Remove from the heat and stir in salt. Set aside to cool for about 10-15 minutes. Once slightly cooled, pour evenly over cooled shortbread cookie layer. Place pan in the fridge for 20-30 minutes.
Melt the Chocolate: In the top bowl of a double boiler, melt chocolate over simmering water until all pieces are melted and smooth. Remove pan from fridge and pour chocolate over top of caramel layer and spread evenly. Return to fridge for about an hour to allow chocolate to cool and harden. Remove from fridge, cut into rectangular bars, and allow the caramel to drip down your chin as you take your first bite of heaven!
Store bars in fridge in airtight container. They will keep for a few weeks if stored properly
These can be messy. Go with it, enjoy it, be messy every once in awhile!