Philips Hue Centura Recessed Spot Light White and Color - Round - Aluminum- 12-pack

Basically, it works, but if you start using the extra options (which is why the product is so expensive), things go wrong and it doesn't work the way it should and the way you paid for.

It's a fine piece of equipment, really, but the thinness of the fixture is completely useless if your transformer is still 4cm thick. So the minimum ceiling depth still needs to be 50mm plus the panel material. Including the raised edge, that easily puts the total ceiling thickness at 70mm. In that case, the fixture might as well be 60mm deep in its entirety, including the electronics. Then you're just stuck with a standard GU10 spot.

If the transformer were a bit thinner (which Ikea can do, for example), there would be no problem.

I think I need to go for a different solution after all.

Make a 7cm hole. Connect the fitting, slide the spotlight over it. Insert the bulb, the sealing ring, and you're done.