In a standing mixer, combine butter, powder sugar, egg and vanilla and mix on medium speed until combined and fluffy
In a large bowl, combine the flour, baking soda, and cream of tartar.
Gradually add in the flour to the wet mixture and mix on low speed until combined
Once dough has formed, place dough onto a lightly floured cutting board
Cut the dough into 4 parts
Take 1/4 of the dough and add green food coloring and mix till combined
Take another 1/4 part of the dough and add red food coloring and mix till combined
You should still have two 1/4 parts
Place a sheet of parchment paper onto the cutting board
Place the red dough onto the parchment paper, sprinkle some flour around it and place another sheet over it
Using a rolling pin, roll out the dough to 1-inch thick rectangle
Cut the edges to clean up the rectangle
Repeat steps with a plain dough
Carefully lift the plain rectangle dough and place it on top of the red dough
Using the parchment paper to help, roll the dough into a log
Cut log in half
Roll one of the half logs into a smaller log for the ears
Fold edges of parchment paper and place cookie logs onto a cookie sheet
Repeat steps with the green and other plain dough
Individually wrap logs with plastic wrap and in the fridge for at least 30 minutes or for as long as overnight
When dough is chilled preheat the oven to 350 degrees
Using a sharp knife, cut the cookie dough logs into 2-inch circles
Place a big circle and two small circles onto the cookie sheet in the shape of Mickey's head. A few drops of water may be needed to help hold the dough together. Gently pinch the ears to the head
Bake in the oven for 8-10 minutes or until slightly golden brown
Once cookies are baked, pick which ones you want to be Minnie and which ones you want to be Mickey
Using the cookie icing, add a small dollop onto the back of the icing bow and place in the middle of the big circle in between the ears
Repeat steps with all Minnie cookies
Using the cookie icing, pipe on a small dot onto the back of the holly sprinkles and place into the top right corner. Tweezers may help with placing holly sprinkles and bows.
Repeat steps with all cookies
Let dry for 20 minutes before enjoying