In advance: Tint melted white candy orange and gray using candy colors (use black to make gray). Tint portion of melted cocoa candy black. Mold castles without pretzels using piping method; chill until firm.
Stir 1 1/2 cups marshmallows and 1/2 cup chopped walnuts into 1 pk. melted cocoa candy. Spoon onto waxed paper-covered Cake Circles, making ovals approx. 3 1/2 x 3 x 1 1/4 in. high. Let set 5-10 minutes; attach castle at center with melted candy. Draw facial features on ghost sprinkles with black FoodWriter. Attach to ovals and castle with melted candy; let set. Place treats in bags.
Adding color details to candies makes them more realistic and much more fun! For large areas of color, it's best to paint the melted candy right in the mold before the whole candy is molded using a decorator brush. Or, for very small details like vines, mouths and messages, melted candy should be piped onto molded candies using a parchment bag with a small hole cut in the tip.