How to Make It
Combine the frosting and food coloring in a small bowl. Transfer the mixture to a pastry bag or plastic bag (snip a small hole in the corner of the bag).
Starting from the center of the cake draw nine lines with the frosting clockwise around the top to the edge. Connect the end of each line to the line next to it with an arched line. Move 1 inch towards the center and draw another series of arcs between the lines. Repeat two more times.
Pipe a small dot of icing for the head of the spider and a larger dot touching it for the body. Pipe four legs on each side of the body. Repeat as desired.