In a large bowl or the bowl of your mixer, combine the butter, sugar, flour, and vanilla until the mixture comes together. Lightly press the shortbread dough into the pan. Prick with a fork to prevent the crust from bubbling. Bake for 35-45 minutes or until the crust is lightly golden. Remove from oven and run a knife around the edges of the bars. Allow to cool completely.

Combine the caramels and cream in a microwave-safe bowl and heat for 3-4 minutes, stirring each minute, until the mixture is smooth. Spread evenly over the cookie crust, then place the pan in the refrigerator and chill for 30-60 minutes or until the caramel is solid.

In a microwave-safe bowl, heat the unwrapped Reese’s Peanut Butter Cups until melted and smooth, stirring each 45 seconds. Spread over the cooled caramel. Place in refrigerator for 1-2 hours or until the chocolate layer is solid. They can also be placed in the freezer for less time if you’re in a hurry. Cut into squares and serve. Store leftovers in a cool area or the refrigerator to prevent messy disasters.