1 tbsp cacao powder
1/2-1 tbsp olive oil (you may need more if you use honey)
1 tbsp sweetener of choice
(this is more to taste so i guessed the amounts)
throw all non-optional ingredients in the blender, then put in ice cream maker according to instructions. you could probably also just freeze it and then whip it up in the food processor later. i guess you could also stir it periodically while freezing it, but that sounds like a lot of work.
the optional ingredients make a fudgy chocolate sauce which tastes really good on top of this. it's also quite good by itself.
note: if you can't get ahold of tahini, you can always just add in around 1/4 cup of sesame seeds in lieu of the butter (or make it yourself in the food processor/vita mix!). other types of nut butters should work, but it's tahini in particular that tastes more like cookie dough or cake batter.