In a large bowl, combine the butter and sugars. Using mixer on medium speed, beat together until creamy. Add the vanilla and beat until combined. Add flour and mix until smooth.
Spray a 9×13 inch baking pan lightly with non-stick cooking spray. Press one-third of the dough evenly into the pan to form a bottom crust.
Place remaining crust mixture in the refrigerator
Preheat oven to 325F.
Bake crust until firm and the edges are a pale golden brown approximately 20 minutes. Transfer to a wire rack and let cool about 15 minutes.
While the bottom crust is baking and the remaining dough is chilling, make the caramel filling. Place the unwrapped caramels in a saucepan, add the cream and vanilla and cook and stir over low to medium heat until completely melted. (You can also use the microwave in short bursts to melt the caramel mixture.)
Pour the caramel filling over the crust. Generously salt with sea salt.
Remove the remaining chilled dough from the refrigerator and crumble it evenly over the caramel. You may find the chilled dough doesn’t “crumble” that easily. If so, just place on a cutting board and chop into the
size pieces you want for the topping.
Return the pan to the oven and bake until the filling is bubbly and the crumbled shortbread topping is firm and lightly golden, about 25 – 30 minutes.
Let cool, and cut into squares.