I made this Hogwarts birthday cake for my sister’s 16th birthday. The whole thing is edible, no cardboard or foam. The base is made of 6 rectangular cakes and the castle and Hagrid’s hut are carved from another 2, the lake is made from blue caramel, the towers are cake with fondant towers and the trees are made from chocolate fondant with green colored desiccated coconut as leaves.
The whole thing was covered in butter icing (~40 packs of butter went into this cake!) before being covered with fondant. Details such as the windows and numbers on the clock were painted on using black food coloring, although an easier option would have been to buy a food coloring pen. I got the idea after watching The Ace of Cakes with my sister who said how cool it would be to have a cake depicting the Hogwarts castle and grounds. Start to finish the cake took about 24 hours.