chocolate cake recipe (that is my standard go to for cakes) but doubled it. I made two 9 inch round cake pans and then I used two round Pyrex dishes. I baked all the cakes at the same time. I let them cool over night and then cut off the tops and sides with a bread knife to ensure the cake was nice and soft. I made a standard butter cream frosting, using organic butter, powdered sugar, vanilla, cream and a dash of salt.
We do not use regular food dyes. All the FDC #'s are forbidden in our house. That's a topic for another day. But what little girl wants plain old white frosting for a princess castle, none that I know. Just because we're dye free doesn't mean we're color free! For the coloring I used freeze dried blueberries and cherries. I made them into a powder in my magic bullet. The cherries were a bit of a problem as they still had juice inside and became leathery, so I took those and dehydrated them over night and then powdered them in the magic bullet. The powder mixed in to the frosting very easily and gave it a wonderful slightly blueberry taste. The top was a light pink as was the frosting between the layers and the rest was purple. This was the easiest and tastiest way I have found to color cakes. I've tried the $9.00 box of "natural" food coloring and it tastes awful and doesn't work that great. Coloring the frosting this way was actually my dear hubby's idea and it worked awesome.
I got gluten free wafer cookies for the door, dye free sun drops and fruit slices from Whole Foods made the windows and decorations. The tower is 3 gluten free ice cream cones frosted and placed together. The flags are fun crazy straws. This was the easiest castle we've every made. It's not super elaborate, but it was perfect for my little princess.
If you are in need of a good food coloring, with out the processing, coal tar and number signs attached try freeze dried fruit next time.