With the mixer fitted with the paddle attachment, beat the butter on medium-low speed for 1 minute. Add in sugar and beat 1-2 minutes until light and fluffy. Beat in vanilla extract and egg yolk. Reduce speed to low and add flour and salt mixture, beating just until dough starts to come together. Do not overmix or the dough will be tough.

Place the dough in a parchment-lined pan and spread evenly. Usually, I use wax paper or a cupcake liner as a barrier between my hands and the dough to get an evenly spread layer. Bake at 350F/180C for 15-20 minutes if using a 12x17 inch pan or 20-25 minutes if using a 9x13 inch pan. Shortbread will appear slightly golden brown when done. Allow pan to cool on a cooling rack while you make your caramel.

Combine all caramel ingredients (sweetened condensed milk, salted butter, brown sugar, light corn syrup, salt, and vanilla) in a saucepan over the stove on medium heat. Stir constantly while making the caramel.

Once it comes to a boil, reduce to low heat. It may take 10-20 minutes of stirring, depending on your heat settings, for the caramel to come together. You'll know it's ready when it pulls away from the sides of the pan easily and has a beautiful, golden caramel color.

Remove the caramel from the heat and spread onto the shortbread layer immediately. Spread the caramel evenly using an offset spatula for good results. Cool in the refrigerator at least 2 hours or overnight, if you wish.

Pour the heavy cream in a small saucepan on the stove over medium-low heat. After 2 minutes, add in the chocolate chips. Stir, stir, stir until the chocolate chips have melted perfectly and created a creamy, thick, chocolaty ganache.

Let the ganache sit for a minute or two before spreading on top of the caramel layer. Again, use an offset spatula to evenly spread the ganache over the cold caramel layer. Sprinkle with sea salt and place in the refrigerator for at least 1 hour to cool completely.

Store bars in refrigerator in an airtight container for up to a week.