Preheat the oven to 325°F (163°C). Lightly spray a 9×13-inch baking dish with nonstick spray.
In the bowl of a stand mixer fitted with the paddle attachment, cream together the butter, granulated sugar, and powdered sugar on medium speed for 2 minutes. Mix in the vanilla until well combined.
On low speed, slowly add the flour and mix until a soft dough forms.
Press half of the dough evenly into the bottom of the prepared baking dish. Wrap the remaining dough in plastic wrap and chill it in the refrigerator.
Bake the pressed dough for 15-20 minutes, until the edges are lightly golden. Remove from the oven and let the crust cool on a wire rack for 15 minutes.
Filling:
In a microwave-safe bowl, combine the unwrapped caramel candies and heavy cream. Microwave on high for 1 minute, then stir until smooth. If the caramel isn’t fully melted, continue microwaving in 30-second intervals, stirring between each, until smooth.
Stir in the vanilla extract and pour the caramel mixture evenly over the cooled crust. Sprinkle with flake sea salt to taste.
Remove the chilled dough from the refrigerator and crumble it evenly over the top of the caramel layer.
Bake for an additional 25-30 minutes, until the caramel is bubbly and the topping is lightly golden brown.
Allow the bars to cool completely before cutting them into 24 squares.