In a large bowl mix the butter and sugar until fluffy, approximately 5 minutes.
When the butter and sugar are fluffy, mix in the vanilla extract and egg.
In a medium-sized bowl, add together the flour, baking powder, and salt. Use a whisk to mix everything together well.
Slowly add the flour mixture to the sugar, butter, egg, and vanilla extract mixture. Mix everything until well incorporated.
Chill your dough for 10 minutes.
Take a 1 1/2 inch scoop of dough and roll into a ball.
Use your finger to create an indent slightly larger than your eyeball sprinkle.
Place the eyeballs onto a sheet pan lined with parchment paper or a silicone mat, bake at 350 for 20 minutes or until the cookies have browned slightly on the edges.
Move the cookies to a cooling rack and allow them to cool completely.
While the cookies are cooling prepare the sugar icing. Mix together the confectionary sugar, water and red food coloring. Keep adding red food coloring until you reach your desired shade of red. To get a nice deep red, you will need quite a bit of food color.
When the cookies are cooled, add a small amount of sugar icing in the indent of your cookie and place the eyeball sprinkle on top, pressing slightly into the icing,
Set aside to dry, about 5 minutes.
Enjoy your spooky treat.