With a mixer on medium speed, cream the butter and confectioner’s sugar until well-mixed.
Add the egg and vanilla extract and beat until fluffy.
On lowest speed, add in the flour and mix well until it makes a soft dough.
On lowest speed, mix in the pecans for just a few seconds. You don't want the dough to turn a brown color from overmixing in the pecans.
On lowest speed, briefly, for just 2 or 3 seconds, mix in the red and green cherries. Do not over mix. You don’t want the cherry colors to bleed into the dough.
Shape the dough into 10-inch long logs and wrap them in waxed paper.
Chill the logs for 1 hour. (You can keep refrigerated for a few days if you want.)
Preheat the oven to 325°.
Use a very thin knife to cut the logs into ⅛- inch slices.
Place the slices on an ungreased or parchment-lined cookie sheet pan.
Bake for 10-12 minutes or until the bottoms are a golden brown.
Remove the cookies from the pan and cool them on a wire rack.
Store the cookies covered at room temperature.