I made this Baby Shower Bathtub Cake for my friends baby shower. I made (2) 13X9 one chocolate and one vanilla. I placed cakes in the freezer for easier handling. Apply frosting to center and add top layer. I cut out the center of the 13X9 to match the size of the plastic container. Frost cake along with the center cut out. I put cake in refrigerator so frosting could set. Once jello has become firm, place into the center of the cake and frost around edge and decorate.
To make water: I used blue jello and filled a small plastic container. As jello started to set I place baby doll so when the jello set, it would hold the doll upright.