Bake 2 8-inch cakes and 1 6-inch cake. Allow the cakes to cool completely. If you cake has a dome, slice the dome off with a knife to make the cake level. Place the first layer of the cake upside down on your cake plate and add a layer of frosting.

Place the second 8-inch cake on top, upside down (it gives it a cleaner surface to frost) and frost it completely. Frost the 6-inch cake on a separate plate.

Prepare the fondant by mircrowaving a bag or marshmallows in a microwave safe bowl for 2 minutes. Add the melted marshmallows to your stand mixer and mix. While mixing, add four tablespoons of water and the bag of powdered sugar one cup at a time until the mixture stiffens. Pull the mixture out and knead it with your hands on a surface covered in powdered sugar. When the fondant has a consistency of a stiff dough, roll the fondant out thin and large enough to cover the cake.

Using both of your arms, lay the fondant over the stacked 8-inch cakes.

Smooth the fondant down and then trim off the excess.

Add the 6-inch frosted cake to the top of the cake and repeat the process. Using the black piping gel add Baymax eyes to the top tier of the cake.