Preheat oven to 350 degrees.
Line a 9x13 baking dish with parchment paper. I find that using small office clips to hold the parchment in place works really well. See picture 4.
In a large mixing bowl or in the bowl of a stand mixer fitted with the paddle attachment, cream the butter, white sugar, and powdered sugar.
Add the vanilla extract.
Beat in the flour.
Press dough into an even layer in the prepared baking dish.
Bake at 350 degrees for 20 minutes.
The edges and top should just barely be slightly golden brown.
Cool on a wire rack for 30 minutes before adding the caramel layer.
Unwrap the caramel squares if necessary.
In a medium saucepan over medium heat, melt the caramels with the heavy cream.
Stir here and there while the caramel melts to prevent scorching.
Once the caramel mixture is completely smooth, remove it from the heat and pour over the shortbread base layer.
Place in the fridge to chill completely (about 30 minutes) before slicing and adding the chocolate layer.
Lift the entire dessert out of the baking dish. I used a spatula to loosen it a little, and then it popped right out.
Set on a large cutting board.
Using a sharp knife, cut in half lengthwise.
Then, slice the halves into sticks or bars a little more than ½ inch in width.
Space the bars out across a sheet of wax paper or parchment paper on a baking sheet.
Melt the chocolate in a melter pot or in a microwave-safe bowl.
Once melted and smooth, drizzle the chocolate topping across the tops of each bar.
This is easiest to do by putting the melted chocolate in a piping bag.
Place in the fridge to set the chocolate.
Now they're ready to eat!
To store, pack them in an airtight container and keep them in the fridge.