Add all cookie ingredients to the mixer bowl and mix on medium speed until combined.
Scoop cookie batter with a cookie scoop (or Tablespoon)and place, evenly spaced, onto a parchment paper-lined cookie sheet.
Bake at 350 degrees for 10 minutes.
Let cool completely on a cooling rack.
For Frosting:
Add frosting and food coloring to the mixer bowl and mix at medium speed until thoroughly combined and frosting is evenly green. Use more or less food coloring to get desired green color.
For making Christmas Cookie Sandwiches:
Spread a cooled cookie with a Tablespoon or two of frosting
Add another cookie to make a cookie sandwich.
Roll the edges of the cookie sandwich in a bowl of green sugar crystals so the sugar crystals stick to the frosting.