Preheat the Oven: Preheat your oven to 350°F (175°C) and grease or line a 12-cup muffin tin with non-stick spray or paper liners.

Prepare the Cookie Dough: In a large mixing bowl, cream together the softened butter and sugar until light and fluffy. Add in the egg, vanilla extract, and salt, mixing well. Gradually add the flour and mix until the dough forms.

Chill the Dough: Chill the dough in the refrigerator for 15-20 minutes to firm it up slightly.

Form the Cookie Cups: Scoop portions of dough and press them into each muffin cup, ensuring an even layer. Press the dough up the sides to form a small crust. Bake for 10-12 minutes or until golden brown around the edges.

Prepare the Caramel: While the cookie cups bake, melt the butter and brown sugar in a saucepan over medium heat. Stir until the sugar dissolves, then bring to a simmer for 2-3 minutes. Remove from heat and add the heavy cream. Stir to combine, then set aside.

Assemble the Cookie Cups: Once the cookie cups have cooled slightly, use the back of a spoon to press an indentation in the center of each cup. Spoon about 1 teaspoon of caramel into each cup.

Add the Chocolate: Melt the chocolate chips either in the microwave in 20-second intervals or over a double boiler. Spoon the melted chocolate over the caramel layer, smoothing it into a glossy finish.

Let Them Set: Allow the chocolate to set either at room temperature or by placing the cookie cups in the refrigerator for 10-15 minutes until the chocolate hardens.

Serve and Enjoy: Once the chocolate has set, serve your Twix Cookie Cups, and enjoy these delightful, bite-sized treats!