Preheat oven to 350°F (175°C). Line an 8x8 inch baking pan with parchment paper.
In a medium bowl, whisk together flour and powdered sugar. Cut in cold butter using a pastry blender or your fingers until the mixture resembles coarse crumbs.
Press the dough into the prepared baking pan. Bake for 15-20 minutes, or until lightly golden.
Meanwhile, melt caramel candies in a double boiler or microwave. Spread evenly over the baked shortbread.
Melt chocolate and spread over the caramel layer. Refrigerate for at least 2 hours before cutting into squares.
Notes
Store leftover shortbread in an airtight container at room temperature.