Preheat oven to 325 degrees F.
Grease 9x9" square pan and set aside.
In a medium bowl whisk together the flour, baking soda, and salt.
In large bowl, beat together melted butter, brown sugar, and granulated sugar with electric mixer until combined.
Add egg, egg yolk, and vanilla extract and beat until smooth.
Slowly add flour mixture on low, and mix until just combined.
Fold in the chocolate chips.
Press half of the cookie dough into prepared pan.
Heat caramel sauce in microwave for 30-45 seconds, then pour caramel over the cookie dough and spread evenly.
Sprinkle with sea salt.
Drop remaining cookie dough over the caramel, then press down to cover caramel.
Sprinkle with additional sea salt.
Bake in preheated oven for 30 minutes, or until top is golden brown and the edges begin to pull away from the edge. It may still seem jiggly.
Cool completely. Cut into squares and enjoy!