My daughter is completely in love with princesses. She knew she wanted a castle cake for her 3rd birthday. I created this cake from two other cake ideas I found on this site. For the cake I used Smitten Kitchen's Best Birthday cake, and her Swiss buttercream frosting. This frosting can be left out overnight. That was key since there was no way this cake was going to fit in my fridge.
I used two 9x13 cakes, and one loaf cake with six straw supports pushed straight through the loaf cake. To make things easier, I baked and froze the cake in advance using freezer paper and jumbo zip lock bags.
The pillars are made from 8 standard ice cream cones and 4 sugar cones. I dipped them in white candy melts, and then dipped again in an attempt to smooth them out. I didn't have success on getting a smooth appearance, but they were coated better. I dipped the sugar cones in blue candy melts, and sprinkled with blue glitter sugar. Once they were dry, I dipped the bottoms of the sugar cones in white melts again, set on top of pillars, and then dipped marshmallows for the stones. Use a toothpick to save your fingers. I also made the pillars in advance.
The day before the party I frosted the cake. Don't frost the corners, because you need to carve out a small section for the pillars. Beware of crumbs. Save some frosting to fill in gaps. I found it easier to pipe on the blue stars on before placing the pillars. I did not want to risk knocking them over. I used yogurt dipped pretzels for stones. I found the princesses at a local cake shop for $10.
The cake looks harder than it is. Break it up over a few days or weeks. Everyone was really impressed.