Preheat oven to 325°F (165°C). Line a 9x13 inch baking pan with parchment paper, leaving an overhang on the sides.

In a large bowl, cream together the butter, granulated sugar, and powdered sugar until light and fluffy.

Mix in the vanilla extract. Gradually add the flour until a soft dough forms.

Press about half of the dough evenly into the bottom of the prepared pan. Refrigerate the remaining dough.

Bake the crust for 20 minutes or until pale golden. Remove and let cool slightly.

While the crust bakes, combine the unwrapped caramels and heavy cream in a saucepan over medium-low heat. Stir constantly until smooth and melted.

Pour the hot caramel over the baked crust, leaving a small gap around the edges.

Crumble the reserved dough over the top of the caramel layer.

Bake for another 25-30 minutes until the filling is bubbly and the topping is golden brown.

Remove from oven and immediately sprinkle with flaky sea salt.

Allow to cool completely to room temperature before cutting into squares.