Using the first stand mixer bowl, combine the remaining powdered sugar, corn syrup, vanilla, and 2 tablespoons of water. Mix until combined with the whisk attachment.

Combine the two icing mixtures into one mixing bowl. Mix on low speed until combined. Stop the machine, scrape the sides, and mix again. Bump up the speed to medium for an additional 2-3 minutes of mixing time If needed to thin the icing, add additional water to the icing one teaspoon at a time until it is thin and a drizzling consistency. Cover the bowl with plastic wrap until ready to decorate. 

Melt the dark chocolate in a microwave-safe bowl, heating in 15-second increments and stirring until smooth. Transfer to a piping bag, and set aside. 

Melt the milk chocolate in a microwave-safe bowl, heating in 15-second increments and stirring until smooth. Transfer to a piping bag, and set aside. 

Place the orange candy melts in a microwave-safe bowl, heating in 15-second increments and stirring until smooth. Transfer to a piping bag, and set aside. 

Cut a small hole in the end of the dark chocolate bag and carefully pipe two eyes on a marshmallow followed by five smaller circles to shape the mouth. Repeat with remaining marshmallows. 

Cut a small hole in the end of the orange candy melt bag and carefully pipe a triangular nose in between the eyes and the mouth on each marshmallow. Set aside. 

Scoop out a spoonful of icing and spread it on each cookie. Get it close to the edge so that occasionally, some icing will spill over but not in excess. Use the back of the spoon to spread where it’s needed. Immediately place your marshmallow head toward the back of the cookie so that the icing is considered the body of the snowman. Repeat with remaining cookies. 

Cut a small hole in the end of the milk chocolate bag and pipe the stick arms on either side of the marshmallow head on each cookie. Repeat with remaining cookies. 

Using the dark chocolate bag again, pipe the coal buttons down the front of the body toward the middle of the cookie. If desired, scatter the “buttons” to reiterate that the snowman is melting and the buttons are askew.  

Allow the icing to set overnight before stacking.