Allow the ingredients to come to room temberature (about 65 degrees). This may take about an hour.
Place a rack in the center of the oven and preheat the oven to 325 degrees F. This may take about half an hour.
Line a baking sheet with parchment paper.
Measure the flour into a bowl.
Sprinkle the maple syrup over the top of the flour and stir.
Add the salt to the flour mixture.
Using the food processor, finely grind half the pecans, stopping before they start to clump. Do not over process the nuts or they will become nut butter. Add the ground pecans to the flour mixture.
Using the food processor, coarsely chop the rest of the pecans. Add the chopped pecans to the flour mixture and stir the flour and nuts together.
Using a stand mixer with a paddle, soften the butter by beating it on medium for about a minute. Do not let the temperature of the butter exceed 68 degrees F.
Add the sugar and cream the butter and sugar on medium for about three minutes, until the mixture is light colored and fluffy.
Reduce the speed to low and add the vanilla, mixing just until the vanilla is incorporated.
Add the flour mixture to the butter mixture and beat on low just until mixed, about 30 seconds. Do not overwork the dough. Scraping down the sides and mix in any remaining flour by hand.
Roll the dough into balls about the size of a walnut and place on the baking sheet about two inches apart.
Bake until they are set, but not browning, about 20 minutes.
Allow the cookies to cool for a minute on the baking sheet.
Place the powdered sugar in a bowl and carefully roll each cookie, one at a time, in the powdered sugar to coat it and then place it on a rack to cool.
When the cookies have cooled, reroll each cookie in the powdered sugar and then give them a final dusting of powdered sugar by sifting some over the top of the cookies.