Store fully cooled Butter Pecan Cookies in an airtight container at room temperature for 4 days. Place a small sheet of parchment between layers so the pecan toppings don't catch. For longer storage, freeze each cookie on a tray for 1 hour. Then seal them in a freezer bag with the air pressed out for up to 2 months. Reheat one room-temperature cookie at 300°F for 3 to 4 minutes. A frozen cookie needs 5 to 7 minutes at the same temperature. Let it rest for 2 minutes before eating because the center stays very hot. Discard cookies that smell rancid, show damp spots or develop an unusually bitter pecan flavor.