Preheat the oven to 350°F. Line a baking sheet with parchment paper (this is a must, candy can be sticky!).
Place the candy bars into an airtight plastic bag and using a mallet, crush into coarse pieces.
In the bowl of your stand mixer fitted with a paddle attachment or large mixing bowl, cream together the butter and sugar until light and fluffy.
Blend in the egg and vanilla.
In another medium bowl, sift together the flour, baking powder and salt. Add half of the flour mixture, blend and then add the remainder. The dough will be thick and dry. Finally, fold in the candy bars.
Use a 1 or 1 1/2 tablespoon cookie scoop and place 2 inches apart on the baking sheet. Using the palm of your hand or the bottom of a glass, flatten to approximately 1/2-1/4 inch thick.
Bake for 11-12 minutes. Cookies will look semi-cooked, this is the time to take them out! If you bake them too long, they won't be chewy. Remove and move to a wire cooling rack.
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