Preheat oven to 350ºF.
Cream butter and sugar together until fluffy.
Add egg, eggnog, and vanilla. Mix well.
Add half of flour, baking powder, salt, and cinnamon. Mix well.
Add remaining flour and mix until well blended.
Stir in craisins.
Work dough with your hands until it forms a ball.
Roll dough into 1-inch balls and place them on a greased cookie sheet.
Flatten each ball with a flat glass cup. Lightly flour the bottom of the cup if it sticks.
Cookies will look nice and smooth on top.
Bake for 10 minutes or until the bottoms are lightly brown. Allow to cool on rack.
To prepare frosting, beat powdered sugar and eggnog together.
If it is too thick, add a little eggnog. If it is too thin, add a bit more powdered sugar.
When cookies are cool, using a brush frost and enjoy every bite!