'Sticking' cake together, quick question

[comeonbishbosh]

Hello,

I've got 3 square chocolate sponges in the freezer which I'm going to defrost and make up as a castle for DD's birthday. One square will from the base and the other I'm planning to cut into walls and turrets, essentially stacked on top.

Any tips on what's my best way of sticking them so it's not too topple-tastic? Could I use a ganashe, or would I better with some form of butter icing, or icing sugar glaze?

Thanks!

I would go with butter icing, you could then use it to "plaster" with if you need more stability.

Thanks greywacke I'll give that a go.