Preheat oven to 325°F. Prepare a 9x13” baking pan with parchment paper. Add flour and salt to a bowl and whisk to combine. In a separate bowl, cream together sugar, butter, and vanilla, until just combined. Add dry ingredients and beat to combine until a crumbly dough forms.

Place dough into baking pan and spread out evenly with your hands. Place a pieces of plastic wrap over top of the surface, then using a flat bottom glass press the dough down to flatten and compact the dough. Remove plastic and place into the oven for 20 minutes, or until it is golden. Remove from the oven and gently press down any puffed up parts. Transfer pan to a cooling rack and allow to cool completely.

Add butter, sugar, corn syrup, and sweetened condensed milk to a medium-large sauce pan over medium-high heat. Stirring constantly, bring the mixture to a boil and then turn down to medium-low. Continue to stir while the mixture simmers for the next 15-25 minutes (Yes, sadly you need to constantly stir the mixture, or else the caramel will begin to burn - good arm workout though haha!). When finished the caramel should be thick and amber-colored.

Remove from heat and stir in the vanilla and bourbon (be careful as the caramel may bubble a bit when you add these). Pour the caramel over top of the cooled shortbread layer and smooth out with a spatula. Place into the fridge for a few hours to cool and set completely.

Place chocolate, corn syrup, and butter into a heat-proof bowl. Place bowl overtop of a pot of simmering water (not boiling), ensuring the bottom of the bowl isn’t touching the water. Stir the mixture until it is completely melted and well combined.

Remove from heat and pour over the cooled caramel layer. Smooth out with a spatula and then allow to sit at room-temperature for 5 minutes. After 5 minutes sprinkle with sea salt and then place into the fridge for an hour or so to set completely.

These shortbread bars should be enjoyed at room temperature or just a bit cooler than room temperature. If you leave them in the fridge for too long the caramel will harden quite a bit and be difficult to eat - so just make sure you take them out of the fridge (if storing there) a few hours before serving!)