I have a castle bundt (nordicware) pan that I wanted to use. Since you can't decorate it with buttercream, my question is can you somehow have a even colored glaze over the whole cake. I was wondering if I could dip the cake in the glaze somehow. I wanted to put this cake on top of a square cake. Any ideas are welcome. Thanks.

you can glaze it with melted chocolate.

can I pour melted chocolate over it? Should I dip it instead?

i wouldnt fancy dipping a cake that size, id take the pouring approach.
you could alo use glace icing, or royal. i think youd need to keep a careful eye on it to make sure the coating doesnt pool anywhere too.
xx