This depends on what you have on hand, how much time you want to spend on the cake, and your skill/what you want it to look like. You could make a bunch of sheet cakes, stack them, and then carve into the shape you want!
You will need a cake pan that is in the shape of a egg, such as a holiday based cake pan used for easter.Or you can buy circular shaped cake pans and bake layers, then cut the layers down to the shape of a bassinet.
