I believe my first anniversary cake settled after completion. It was all buttercream with BC between the layers. I used stiff to pipe a damn around the edge prior to placement of top layer. Any ideas how to prevent this in the future?

Allow the cake to rest for a few hours after filling it. You can seal it with a crumb coat of icing before letting it rest to keep in the cake's moisture.

I torte, fill then wrap my cakes in plastic and try to let them sit for 24 hours before putting on the finish coat of icing. You have to let them settle.

I do the same as leahs with an added step -- I place a couple of empty cake pans on top of the wrapped, resting cake to help compress it.

ooooo good idea!

Thank you very much for your input, I am eager to try these techniques soon.