Preheat the oven to 350°F (175°C).

In a mixing bowl, cream together the softened butter, granulated sugar, and brown sugar until smooth.

Add the egg and vanilla extract, and mix until fully incorporated.

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

Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Scoop the cookie dough into a greased muffin tin, filling each cup about halfway.

Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden.

Remove from the oven and let cool for 5 minutes.

Using the back of a spoon, press down the center of each cookie to create a cup shape.

Fill each cookie cup with caramel sauce and sprinkle with chopped peanuts if desired.

In a microwave-safe bowl, combine chocolate chips and vegetable oil. Microwave in 30-second intervals, stirring until smooth.

Drizzle the melted chocolate over the filled cookie cups.

Allow to cool completely before serving.