What's the fastest method to cool this cake?

Seag, I understand your confusion. The recipe gives you no information of how/how long to cool it, nor how to de-pan it. I live in a climate which is relatively cold right now. I'm fond of using my garage as walk-out cold storage this time of year, so I would set it right on the cold concrete floor, making sure the door is closed against curious dogs and cats - especially dogs - and leave it there until completely cooled. If such a space isn't available to you, set it on the lowest shelf of your refrigerator.

Hello!

I would recommend cooling this cake in the pan on a counter for about an hour before putting it into the fridge. If you have a full fridge (as most of us do around this time) putting it in too warm could risk heating up the interior of the fridge to unsafe temperatures. After it is cool to the touch it should be good to unmold!