Preheat your oven to 350°F (175°C).
Grease your muffin tin with cooking spray or line it with muffin liners.
In a large mixing bowl, combine the melted butter, light brown sugar, granulated sugar, egg, and vanilla extract. Whisk until smooth and well blended.
In a separate bowl, whisk together the all-purpose flour, cornstarch, baking soda, and a pinch of salt. Gradually add this dry mixture to the wet ingredients, stirring until just combined.
Gently fold the semi-sweet chocolate chips into the cookie dough using a rubber spatula.
Using a cookie scoop, portion the dough into the prepared muffin tin, filling each cup about halfway. Press a Werthers Original Baking Caramel into the center of each dough portion, then cover the caramel with more dough.
Place the muffin tin in the preheated oven and bake for 10-12 minutes or until the edges are lightly golden and the centers look slightly underbaked.
Let the cookie cups cool in the tin for about 5 minutes before transferring them to a wire rack.