The organic Thai kitchen tends to thicken well! Brands are different but typically you can turn the can upside down and drain out the coconut water and use the rest.I found a recipe for a coconut milk mousse on Pinterest yesterday. It calls for something like 1/4 cup of dutch cocoa powder plus coconut cream (the thick part from a refrigerated/separated can of full-fat coconut milk). The 365 brand from Whole Foods never gets very solid for me when I refrigerate it, so I will have to try it with some other brand. I think Native Forest worked for me before. I wish we had a better mixer. I wonder if I could find whisk attachments for our cheapo hand/stand mixer (it can be removed from the stand). It just uses the standard hand mixer kind of attachments.
I don't know if you have a trader joes around by you, but their I can get actual canned coconut cream, which works really well for mousse! Although I did have to water it down a bit.