This is a homemade 1/2-sheet butter cake, covered in white "chocolate plastic" and decorated with meringue buttercream frosting. The design of Mike and Sully is adapted from the movie DVD cover.
I made several practice crayon sketches on paper, then sketched in the basic shapes on the cake using an art paintbrush dipped in tinted frosting thinned with water. Then I piped icing over the sketch. I created contrast on Sully by using blue and turquoise. I used very fine black piping sparingly, in their eyes, mouths, horns and Mike's claws.
I put a thin layer of buttercream over the cake, and then the "chocolate plastic" (melt 1 lb white chocolate in the microwave, stir in 1/2 c light corn syrup, turn out onto plastic wrap, cool completely, knead a little, then roll and shape like fondant use powdered sugar to help roll it out).
The buttercream is 2-1/2 c sugar, 9 egg whites & 2 T water (heated to 160F over boiling water, stirring constantly, then whipped to stiff peaks 8 minutes in stand mixer) then 2 lbs (!)room-temp organic butter beaten in.
I used a total of 5 colors of icing on this cake, including the white, using Wilton gel colors. I mixed Sully's turquoise by using blue and green, and Mike's green using green and yellow. The purple is a mix of purple and pink. I think the colors turned out a little too dark -- once the gel color starts developing in the frosting, it just keeps getting darker, so take your time tinting the frosting. It would be a good idea to make a practice batch of frosting to work with colors and different piping tips -- I ran out of time and was racing to finish this cake before my son's party. Still, I think it turned out well. Hope you enjoyed viewing it.