To make a snowman cookie with top hat you will need:

 Cut out a cupcake cookie and a circle cookie and piece them together as shown

Outline and flood the hat portion with black glaze.

To prevent bleeding, allow it to dry for a few hours before 

outlining and flooding the circle with white glaze.

Allow the cookie to dry overnight.

 Using black and orange glaze, add eyes and a carrot nose.

 Use a food color marker to make a mouth, eyebrows, or any other details you'd like.

Feel free to embellish the hat with a colorful flower, holly leaves, or band around the base.