Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a large bowl, cream together the softened butter, granulated sugar, and brown sugar using a mixer until light and fluffy, about 2-3 minutes.

Incorporate the egg and vanilla extract, mixing until fully blended.

In a separate bowl, whisk together the all-purpose flour, baking soda, and salt.

Gradually add the dry ingredients to the wet mixture, mixing gently to combine. Avoid overmixing.

Fold in the crushed shortbread cookies, distributing them evenly through the dough.

Use a cookie scoop or a tablespoon to drop rounded portions of dough onto the prepared baking sheet, spacing them about 2 inches apart.

Bake in the preheated oven for 10-12 minutes until the edges are golden brown.

Press the back of a spoon into the center of each cookie to create a small indentation.

Meanwhile, prepare the caramel filling by melting the chewy caramel candies and heavy cream together in a small saucepan over low heat, stirring continuously until smooth.

Spoon a bit of melted caramel into the center of each cookie.

Transfer cookies to a wire rack to cool completely.

Melt the milk chocolate chips with the vegetable oil in a microwave-safe bowl, stirring until smooth.

Drizzle the melted chocolate over the cooled cookies using a fork or piping bag.

Let the chocolate set before serving or storing.