Preheat your oven to 350°F (175°C).
Line a 9x13 inch baking pan with parchment paper.
In a large mixing bowl, combine the softened butter, light brown sugar, and granulated sugar. Cream on medium speed until light and fluffy, about 2-3 minutes.
Add the eggs one at a time, mixing well after each addition. Then add the vanilla extract and mix until fully incorporated.
In a separate bowl, whisk together the flour, kosher salt, and baking soda. Gradually add to the wet ingredients, mixing on low speed until just combined.
Gently fold in the semisweet chocolate chips with a spatula.
Spread half of the cookie dough into the prepared pan and bake for 10-12 minutes.
While the cookie base is baking, melt the unwrapped caramels and sweetened condensed milk in a small saucepan over low heat, stirring continuously.
Once the cookie base is baked, pour the caramel mixture evenly over the warm cookie layer.
Dollop the remaining cookie dough over the caramel layer.
Return to the oven and bake for an additional 20-25 minutes until golden brown.
Sprinkle the flaked sea salt over the top as soon as you take the bars out of the oven.
Allow to cool completely in the pan on a wire rack, then cut into squares.
