Ungreased cake pan

You might consider making a trifle or similar dessert, cutting or pulling out what you can, and layering it (when cool) with custard or whipped cream and fresh fruit. When my batter stuck to a new Bundt pan (despite greasing the pan) there wasn't much I could do. I tore out large chunks, devoured them (they were delicious, as yours will be) and called it a day.

If anyone has an answer for this I'd be glad to hear it. You can cut around the sides, of course, but you'll probably have to trust your stars for the rest. The cake will be less prone to self destruct if it's cool, but may stick more, too. Turn it over and whack it plenty.
I could conceive of cutting it in half and trying to get a spatula under each side with as little damage as possible; might work for a cake with a lot of frosting, but I've never tried it and hope I never do. Best of luck.