Salted Caramel Shortbread Ingredients for the shortbread layer: 10 tbsp unsalted butter, at room temperature 1/2 cup sugar 1/2 tsp salt 1 egg yolk 1-2/3 cups flour for the caramel: 1 cup unsalted butter 1 cup light brown sugar 3/4 cup light corn syrup 2 tsp sea salt, plus more for sprinkling on top 4