Step 1

Preheat oven to 350 degrees F. Lightly grease an 8x8-inch baking pan and set aside.

Step 2

In a large mixing bowl, combine sugar and flour. Add cold butter cubes and mix in (I use my clean hands to really get in there and knead everything together) until butter is evently incorporated and shortbread dough resembles wet sand. Press evenly into bottom of prepared pan.

Step 3

Bake in preheated oven for 12-15 minutes, until lightly golden. Allow to cool while you make your caramel layer--I usually pop the pan directly into the freezer for 10 minutes.

Step 4

Melt butter in a medium saucepauce over medium heat. Add remaining ingredients and mix until smooth. Heat, stirring occasionally, over low heat until mixture comes to a boil. Continue simmering, stirring constantly, for 5 minutes over low heat until mixture turns an amber color and thickens slightly. Turn off heat, add sea salt, and continue beating vigorously for 3 minutes. Pour evenly over cooled shortbread crust and transfer pan to refrigerator for 1 hour. (In a pinch, you can also pop it in the freezer for 30 minutes while making your chocolate layer.)

Step 5

Place chocolate chips in a medium microwave-safe bowl and heat for 30 seconds. Stir chocolate mixture, then heat in additional 15-second increments as needed until chocolate is completely melted and smooth when stirred.

Step 6

Pour evenly over caramel layer. Cover pan with foil and refrigerate for an additional 1-2 hours before slicing into 36 small squares and serving.