Cream together butter, cream cheese, and sugar. Add in egg and vanilla and stir well. Add 1 cup of flour to wet ingredients at a time, stirring each time. Then add salt and stir. Fold in chopped pecans.
Divide batter in half. Roll into 4 logs each about 2″ across. Wrap in plastic wrap and place in refrigerator to firm up for at least 2 hours.
Preheat oven to 325˚F. Place red crystals on a plate or tray, and green sugar on a separate plate. Roll 2 logs in red sugar and remaining logs in green sugar. Using a very sharp knife cut each log into slices 1/4″ slices. If reusing same tray, knife, and other tools wash and dry them well between colors to avoid accidentally mixing the red and green.
Place on lined baking sheet 2″ apart. Place a pecan half in the center of each cookie and bake for 15-18 minutes or until bottom of cookies begins to brown slightly. Do not overbake.