I followed the instructions for the “anatomically correct” lego cake. I cut a 9X13 sheet cake into thirds and layered them. For the squares, I cut the thirds in half. Very simple, just time-consuming.
Baking and freezing the cakes ahead of frosting works well, and allows you lots of time and energy for the frosting part. I made a lot of frosting (used a wedding cake/bakery-style recipe that worked very well for this challenging-to-frost cake) and used marshmallows for the tops. In the future, I would recommend gel colors to get more primary colors (standard colors are more pastel) and I would highly suggest using mini-muffins for tops, as it turns out marshmallows are not so easy to frost!
But with a lot of patience, these Lego cakes for Lego lovers came out great and the kids loved it.