Step 1: Preheat oven to 325°F (165°C) and lightly grease a 24-cup mini muffin tin.
Step 2: In a large bowl, cream together softened butter, granulated sugar, and powdered sugar until light and fluffy.
Step 3: Gradually mix in flour and salt until a soft dough forms.
Step 4: Roll dough into 1-inch balls and press into prepared muffin cups, forming small cups.
Step 5: Bake for 18-20 minutes or until edges are lightly golden.
Step 6: Remove from oven and immediately use the back of a spoon to gently press down centers to reshape cups.
Step 7: Let cool in pan for 5 minutes, then transfer to a wire rack to cool completely.
Step 8: Fill each cookie cup with about 1 teaspoon of caramel sauce.
Step 9: Drizzle additional caramel sauce over the tops and sprinkle with sea salt flakes if desired.
Step 10: Let set for 10 minutes before serving.