In the bowl of a stand mixer (a stand mixer works better with the cold butter), beat cold butter, brown sugar, confectioners’ sugar, cinnamon and salt together until combined.
Scrape down the bottom and the sides of the bowl as necessary. Add egg yolk and mix until combined.
Add flour and mix just until combined.
Next. add the chopped pecans and mix until incorporated.
Transfer dough to a lightly floured work surface and roll into a 12-inch log about 2 inches in diameter. Wrap dough log in plastic wrap and chill for at least 1 hour.
Preheat oven to 350 F. Line a baking sheet with parchment paper and set aside. Remove dough log from the refrigerator and discard the plastic wrap.
Use a sharp knife to cut the dough into discs about ¼-inch to ½-inch thick. Add the sliced dough onto the prepared baking sheet.
Garnish the cookie dough slices with pecan halves.
Bake at 350 F for 12 minutes or until golden around the edges.
Allow cookies to cool on the pan for a few minutes before transferring to a wire rack to cool completely.