Add all the ingredients to your Ninja Creami container and stir to combine.
Freeze on a level surface for at least 18 hours.
Remove from the freezer and process on the light ice cream setting. If needed, respin.
Notes
Use plain, unsweetened yogurt. If you use regular yogurt, the chocolate flavor should shine through. If you use Greek yogurt that is a little more tangy, expect the tang to come through and it to taste a little cheesecake-ish (however Greek yogurt typically does have more protein).
I usually run a little warm water on the outside to the pint before processing. You can also leave out for 5-10 minutes to thaw slightly before processing.
If you have leftovers (I didn't lol), you can smooth out the top and return it to the freezer! You may need to thaw or reprocess before enjoying again.