Preheat the oven to 350ºF.
In a bowl, mix the flour, baking soda and salt.
In a separate bowl, whisk together the butter, brown and white sugar, egg yolk and vanilla extract.
Mix in the flour, and then add the chopped TWIX® Cookies & Creme bars. Mix until evenly distributed.
Divide the mix between 12 cupcake liners, in a cupcake tray.
Bake for 20 minutes.
Meanwhile, whisk together the cream cheese and sugar, then whisk in the egg until smooth.
Spoon the topping over the baked bases, and decorate with TWIX® Cookies & Creme slices.