Arrange an oven rack to the middle position. Preheat to 300°F. Line two baking sheets with parchment and set aside.
Using an electric handheld mixer, beat the butter and sugar until light colored and very fluffy. Add flour and salt and continue to mix on the lowest speed until the ingredients are incorporated. Dough will very crumbly.
Add the chocolate dust and using your hands, gently work into the dough until speckled throughout.
Load the dough into a gallon-sized plastic bag. Keeping the zip top of the bag open, carefully rollout on a flat surface. Be sure to roll the dough to every edge and into every corner of the bag. Then roll to an even thickness overall. Seal top of bag and refrigerate for at least one hour.
Remove the dough bag from the refrigerator and use scissors to cut the bag off the dough. Using your favorite cookie cutter(s), cut 25 cookies from dough. Place 10 to 14 cookies on each sheet depending on size and bake each sheet for 20 minutes. Cookies will just be starting to turn light brown. Cool completely on a wire cooling rack to avoid crumbling when handling.