Either refrigerate the coconut milk can overnight, or open and freeze about 10 minutes. (I store a can in the fridge so there’s always one ready to go. Be sure to use full-fat canned coconut milk for this recipe. Try not to shake the can, because you want the cream separate from the water underneath.)
Once cold, open the can and transfer only the thick part to a bowl. Discard the watery part, or save for another recipe. Using either a stand mixer or hand beaters (or a fork and a ton of strength and patience), whip the cream until smooth. Add remaining ingredients and whip until it forms a mousse-like texture.

Notes

Be sure to check out the video above of how to make the chocolate mousse! Very rarely, you may get a can of coconut milk that is chalky and hard or won’t firm up, so I like to always keep two cans from different brands on hand just in case. This recipe was adapted from my recipe for Coconut Whipped Cream.