Making a birthday cake for a kid's birthday party-- not the suggested method:
1) The morning of the party, bake the cake he wants (chocolate raspberry) in the fancy castle bundt pan:
2) Completely fail to get it out of the pan, ending up with 7 or 8 large chunks.
2.5) Be glad the party is for the 12 year old, not the (nearly) 5 year old, or else you'd be baking a second cake.
3) Buy a quart of vanilla ice cream, and a pint of heavy cream.
4) Scoop the ice cream into a large bowl, and mix is the most of the cake Press almost all the leftovers into the bottom of a springform pan, saving a few chunks to console the somewhat unhappy birthday boy (and his younger brother).
5) Mash the cake/ice cream blend into the pan. Put it in the freezer -- oops:
5.5) Make space in the freezer for a springform pan.
6) Put cake in the freezer. Wait half an hour.
7) Add about 5 oz of chocolate to a cup of heavy cream, and microwave it on medium power until the chocolate melts. Stir until homogenous, and them pour it over the cake. Put it back in the freezer. Rearrange everything in the freezer until the cake is nearly level. Leave it there until the party.
It worked really well, in the end. Yay.