When I was a kid oh so long ago, my dad went on sabbatical in France when I was in 4th grade. I picked up a recipe for chocolate mousse that's pretty close to being primal...
2 oz butter
5 oz dark chocolate
1. Start melting butter and chocolate together. I suggest using a double-boiler, but anything that'll make sure they don't burn should be fine.
2. Separate eggs. Mix yolks in one small bowl; in a separate (larger!) bowl, whip the whites until they're quite firm.
3. Mix the hot melted butter & chocolate together and remove from heat. Then slowly pour the yolks into the butter/chocolate, stirring all the while, so you have a homogeneous mixture. The yolks cook a bit in this step.
4. Gently fold the butter/chocolate/yolks into the whites.
5. Refrigerate (covered if possible). For a single batch, 3 hours is probably sufficient to get it to set properly.
This recipe makes a very rich mousse; a fairly small serving suffices to satisfy!
I just made this the other night for the first time since going primal, and it was excellent, even though I screwed up and only put in half the butter. Great success! FWIW, I used 78% cocoa dark chocolate from Santa Barbara Chocolate Co., and it was plenty sweet; my non-primal guests loved it, or at least made convincing noises to that effect.
This recipe might also be good if made with coconut oil instead of butter; if you try making it that way, please let me (and the world) know how it comes out.